From R to CFF

Crosswalk

Diego Hernangómez

The goal of this vignette is to provide an explicit map between the metadata fields used by cffr and each one of the valid keys of the Citation File Format schema version 1.2.0.

Summary

We summarize here the fields that cffr can coerce and the original source of information for each one of them. The details on each key are presented in the next section of the document. The assessment of fields is based on the Guide to Citation File Format schema version 1.2.0 (Druskat et al. 2021).

key source
abstract DESCRIPTION file
authors DESCRIPTION file
cff-version argument on function
commit DESCRIPTION file
contact DESCRIPTION file
date-released DESCRIPTION file
doi CITATION file
identifiers DESCRIPTION/CITATION files
keywords DESCRIPTION file
license DESCRIPTION file
license-url Ignored by cffr
message DESCRIPTION file
preferred-citation CITATION file
references DESCRIPTION/CITATION files
repository DESCRIPTION file
repository-artifact Ignored by cffr
repository-code DESCRIPTION file
title DESCRIPTION file
type Fixed value: ‘software’
url DESCRIPTION file
version DESCRIPTION file
Table 1: cffr and R packages: Conversion table

Details

abstract

This key is extracted from the "Description" field of the DESCRIPTION file.

Example 
library(cffr)

# Create cffr for yaml

cff_obj <- cff_create("rmarkdown")

# Get DESCRIPTION of rmarkdown to check

pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(cff_obj$abstract)
#> Convert R Markdown documents into a variety of formats.

cat(pkg$get("Description"))
#> Convert R Markdown documents into a variety of formats.

Back to Table 1.

authors

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. By default persons with the role "aut" or "cre" are considered, however this can be modified via the authors_roles argument.

Example 
# An example DESCRIPTION
path <- system.file("examples/DESCRIPTION_many_persons", package = "cffr")
pkg <- desc::desc(path)

# See persons listed
pkg$get_authors()
#> [1] "Diego Hernangómez <fake@gmail.com> [aut, cre] (ORCID: <https://orcid.org/0000-0001-8457-4658>, email: error, not-valid: error)"
#> [2] "Joe Doe <I am a wrong email> [aut] (affiliation: This One, country: ES, date-end: error)"                                      
#> [3] "Pepe Doe <fake@gmail.com> [aut] (error)"                                                                                       
#> [4] "I am an entity [cre] (date-end: 2020-01-01, affiliation: error)"                                                               
#> [5] "ERROR entity [cph] (for the administrative boundaries.)"                                                                       
#> [6] "ERROR person [cph] (ORCID: <https://orcid.org/0000-0003-2042-7063>, for the gisco_countrycode dataset.)"

# Default behaviour, use authors and creators (maintainers)
cff_obj <- cff_create(path)
cff_obj$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: fake@gmail.com
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - family-names: Doe
#>   given-names: Joe
#>   affiliation: This One
#>   country: ES
#> - family-names: Doe
#>   given-names: Pepe
#>   email: fake@gmail.com
#> - name: I am an entity
#>   date-end: '2020-01-01'

# Use now Copyright holders and maintainers
cff_obj_alt <- cff_create(path, authors_roles = c("cre", "cph"))
cff_obj_alt$authors
#> - family-names: Hernangómez
#>   given-names: Diego
#>   email: fake@gmail.com
#>   orcid: https://orcid.org/0000-0001-8457-4658
#> - name: I am an entity
#>   date-end: '2020-01-01'
#> - name: ERROR entity
#> - family-names: person
#>   given-names: ERROR
#>   orcid: https://orcid.org/0000-0003-2042-7063

Back to Table 1.

cff-version

This key can be set via the arguments of the cff_create()/cff_write() functions:

Example 
cff_objv110 <- cff_create("jsonlite", cff_version = "v1.1.0")

cat(cff_objv110$`cff-version`)
#> v1.1.0

Back to Table 1.

commit

This key is extracted from the "RemoteSha" field of the DESCRIPTION file. This is the case of packages installed using the r-universe or packages such as remotes or pak.

Example 
# An example DESCRIPTION
path <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
pkg <- desc::desc(path)

# See RemoteSha
pkg$get("RemoteSha")
#>                                  RemoteSha 
#> "bdd9a29d7eabcc43c3195fe461f884932eba763c"

cff_read(path)
#> cff-version: 1.2.0
#> message: 'To cite package "codemetar" in publications use:'
#> type: software
#> title: 'codemetar: Generate ''CodeMeta'' Metadata for R Packages'
#> version: 0.3.5
#> authors:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: cboettig@gmail.com
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> - family-names: Salmon
#>   given-names: Maëlle
#>   orcid: https://orcid.org/0000-0002-2815-0399
#> abstract: The 'Codemeta' Project defines a 'JSON-LD' format for describing software
#>   metadata, as detailed at <https://codemeta.github.io>. This package provides utilities
#>   to generate, parse, and modify 'codemeta.json' files automatically for R packages,
#>   as well as tools and examples for working with 'codemeta.json' 'JSON-LD' more generally.
#> repository: https://ropensci.r-universe.dev
#> repository-code: https://github.com/ropensci/codemetar
#> url: https://docs.ropensci.org/codemetar/
#> date-released: '2024-02-09'
#> contact:
#> - family-names: Boettiger
#>   given-names: Carl
#>   email: cboettig@gmail.com
#>   orcid: https://orcid.org/0000-0002-1642-628X
#> keywords:
#> - metadata
#> - codemeta
#> - ropensci
#> - citation
#> - credit
#> - linked-data
#> - json-ld
#> - peer-reviewed
#> - r
#> - r-package
#> - rstats
#> license: GPL-3.0-only
#> commit: bdd9a29d7eabcc43c3195fe461f884932eba763c
#> doi: 10.32614/CRAN.package.codemetar

Back to Table 1.

contact

This key is coerced from the "Authors" or "Authors@R" field of the DESCRIPTION file. Only persons with the role "cre" (i.e, the maintainer(s)) are considered.

Example 
cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cff_obj$contact
#> - family-names: Xie
#>   given-names: Yihui
#>   email: xie@yihui.name
#>   orcid: https://orcid.org/0000-0003-0645-5666

pkg$get_author()
#> [1] "Yihui Xie <xie@yihui.name> [aut, cre] (ORCID: <https://orcid.org/0000-0003-0645-5666>)"

Back to Table 1.

date-released

This key is extracted from the DESCRIPTION file following this logic:

Example 
# From an installed package

cff_obj <- cff_create("rmarkdown")
pkg <- desc::desc(file.path(find.package("rmarkdown"), "DESCRIPTION"))

cat(pkg$get("Date/Publication"))
#> 2025-09-28 11:30:02 UTC

cat(cff_obj$`date-released`)
#> 2025-09-28

# A DESCRIPTION file without a Date
nodate <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp <- tempfile("DESCRIPTION")

# Create a temporary file
file.copy(nodate, tmp)
#> [1] TRUE

pkgnodate <- desc::desc(tmp)
cffnodate <- cff_create(tmp)

# Won't appear
cat(cffnodate$`date-released`)

pkgnodate
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Adding a Date

desc::desc_set("Date", "1999-01-01", file = tmp)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Date: 1999-01-01
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)$`date-released`)
#> 1999-01-01

Back to Table 1.

doi

This key is coerced from the "doi" field of the preferred-citation object. If not present and the package is on CRAN, it would be populated with the doi provided by CRAN (e.g. https://doi.org/10.32614/CRAN.package.cffr).

Example 
cff_doi <- cff_create("cffr")

cat(cff_doi$doi)
#> 10.21105/joss.03900

cat(cff_doi$`preferred-citation`$doi)
#> 10.21105/joss.03900

Back to Table 1.

identifiers

This key includes all the possible identifiers of the package:

Example 
file <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

pkg <- desc::desc(file)

cat(pkg$get_urls())
#> https://github.com/test/package https://test.github.io/package/ https://r-forge.r-project.org/projects/test/ http://google.ru https://gitlab.com/r-packages/behaviorchange

cat(cff_create(file)$url)
#> https://test.github.io/package/

cat(cff_create(file)$`repository-code`)
#> https://github.com/test/package

cff_create(file)$identifiers
#> - type: url
#>   value: https://r-forge.r-project.org/projects/test/
#> - type: url
#>   value: http://google.ru
#> - type: url
#>   value: https://gitlab.com/r-packages/behaviorchange

Back to Table 1.

keywords

This key is extracted from the DESCRIPTION file. The keywords should appear in the DESCRIPTION as:

...
X-schema.org-keywords: keyword1, keyword2, keyword3
Example 
# A DESCRIPTION file without keywords
nokeywords <- system.file("examples/DESCRIPTION_basic", package = "cffr")
tmp2 <- tempfile("DESCRIPTION")

# Create a temporary file
file.copy(nokeywords, tmp2)
#> [1] TRUE

pkgnokeywords <- desc::desc(tmp2)
cffnokeywords <- cff_create(tmp2)

# Won't appear
cat(cffnokeywords$keywords)

pkgnokeywords
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

# Adding Keywords

desc::desc_set(
  "X-schema.org-keywords",
  "keyword1, keyword2, keyword3",
  file = tmp2
)
#> Type: Package
#> Package: basicdesc
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000
#> X-schema.org-keywords: keyword1, keyword2, keyword3

cat(cff_create(tmp2)$keywords)
#> keyword1 keyword2 keyword3

Additionally, if the source code of the package is hosted on GitHub, cffr can retrieve the topics of the repository via the GitHub API and include those topics as keywords. This option is controlled via the gh_keywords argument:

Example 
# Get cff object from jsonvalidate

jsonval <- cff_create("jsonvalidate")

# Keywords are retrieved from the GitHub repo

jsonval
#> cff-version: 1.2.0
#> message: 'To cite package "jsonvalidate" in publications use:'
#> type: software
#> license: MIT
#> title: 'jsonvalidate: Validate ''JSON'' Schema'
#> version: 1.5.0
#> doi: 10.32614/CRAN.package.jsonvalidate
#> abstract: Uses the node library 'is-my-json-valid' or 'ajv' to validate 'JSON' against
#>   a 'JSON' schema. Drafts 04, 06 and 07 of 'JSON' schema are supported.
#> authors:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: rich.fitzjohn@gmail.com
#> - family-names: Ashton
#>   given-names: Rob
#> - family-names: Buus
#>   given-names: Mathias
#> - family-names: Poberezkin
#>   given-names: Evgeny
#> repository: https://CRAN.R-project.org/package=jsonvalidate
#> repository-code: https://github.com/ropensci/jsonvalidate
#> url: https://docs.ropensci.org/jsonvalidate/
#> date-released: '2025-02-07'
#> contact:
#> - family-names: FitzJohn
#>   given-names: Rich
#>   email: rich.fitzjohn@gmail.com
#> keywords:
#> - json
#> - json-validation
#> - jsonvalidate
#> - r
#> - r-package
#> - rstats
#> references:
#> - type: software
#>   title: R6
#>   abstract: 'R6: Encapsulated Classes with Reference Semantics'
#>   notes: Imports
#>   url: https://r6.r-lib.org
#>   repository: https://CRAN.R-project.org/package=R6
#>   authors:
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.R6
#> - type: software
#>   title: V8
#>   abstract: 'V8: Embedded JavaScript and WebAssembly Engine for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/V8
#>   repository: https://CRAN.R-project.org/package=V8
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.V8
#> - type: software
#>   title: knitr
#>   abstract: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Suggests
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.knitr
#> - type: software
#>   title: jsonlite
#>   abstract: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Suggests
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: rmarkdown
#>   abstract: 'rmarkdown: Dynamic Documents for R'
#>   notes: Suggests
#>   url: https://pkgs.rstudio.com/rmarkdown/
#>   repository: https://CRAN.R-project.org/package=rmarkdown
#>   authors:
#>   - family-names: Allaire
#>     given-names: JJ
#>     email: jj@posit.co
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   - family-names: Dervieux
#>     given-names: Christophe
#>     email: cderv@posit.co
#>     orcid: https://orcid.org/0000-0003-4474-2498
#>   - family-names: McPherson
#>     given-names: Jonathan
#>     email: jonathan@posit.co
#>   - family-names: Luraschi
#>     given-names: Javier
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevin@posit.co
#>   - family-names: Atkins
#>     given-names: Aron
#>     email: aron@posit.co
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@posit.co
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.rmarkdown
#> - type: software
#>   title: testthat
#>   abstract: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#> - type: software
#>   title: withr
#>   abstract: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: krlmlr+r@mailbox.org
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevinushey@gmail.com
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr

# Check keywords
jsonval$keywords
#> [1] "json"            "json-validation" "jsonvalidate"    "r"              
#> [5] "r-package"       "rstats"

# The repo
jsonval$`repository-code`
#> [1] "https://github.com/ropensci/jsonvalidate"

Back to Table 1.

license

This key is extracted from the "License" field of the DESCRIPTION file.

Example 
cff_obj <- cff_create("yaml")

cat(cff_obj$license)
#> BSD-3-Clause

pkg <- desc::desc(file.path(find.package("yaml"), "DESCRIPTION"))

cat(pkg$get("License"))
#> BSD_3_clause + file LICENSE

Back to Table 1.

license-url

This key is not extracted from the metadata of the package. See the description on the Guide to CFF schema v1.2.0.

Back to Table 1.

message

This key is extracted from the DESCRIPTION field, specifically as:

msg <- paste0(
  'To cite package "',
  "NAME_OF_THE_PACKAGE",
  '" in publications use:'
)
Example 
cat(cff_create("jsonlite")$message)
#> To cite package "jsonlite" in publications use:

Back to Table 1.

preferred-citation

This key is extracted from the CITATION file. If several references are provided, it would select the first citation as the "preferred-citation" and the rest of them as references.

Example 
cffobj <- cff_create("rmarkdown")

cffobj$`preferred-citation`
#> type: manual
#> title: 'rmarkdown: Dynamic Documents for R'
#> authors:
#> - family-names: Allaire
#>   given-names: JJ
#>   email: jj@posit.co
#> - family-names: Xie
#>   given-names: Yihui
#>   email: xie@yihui.name
#>   orcid: https://orcid.org/0000-0003-0645-5666
#> - family-names: Dervieux
#>   given-names: Christophe
#>   email: cderv@posit.co
#>   orcid: https://orcid.org/0000-0003-4474-2498
#> - family-names: McPherson
#>   given-names: Jonathan
#>   email: jonathan@posit.co
#> - family-names: Luraschi
#>   given-names: Javier
#> - family-names: Ushey
#>   given-names: Kevin
#>   email: kevin@posit.co
#> - family-names: Atkins
#>   given-names: Aron
#>   email: aron@posit.co
#> - family-names: Wickham
#>   given-names: Hadley
#>   email: hadley@posit.co
#> - family-names: Cheng
#>   given-names: Joe
#>   email: joe@posit.co
#> - family-names: Chang
#>   given-names: Winston
#>   email: winston@posit.co
#> - family-names: Iannone
#>   given-names: Richard
#>   email: rich@posit.co
#>   orcid: https://orcid.org/0000-0003-3925-190X
#> year: '2025'
#> notes: R package version 2.30
#> url: https://github.com/rstudio/rmarkdown

citation("rmarkdown")[1]
#> Allaire J, Xie Y, Dervieux C, McPherson J, Luraschi J, Ushey K, Atkins
#> A, Wickham H, Cheng J, Chang W, Iannone R (2025). _rmarkdown: Dynamic
#> Documents for R_. R package version 2.30,
#> <https://github.com/rstudio/rmarkdown>.
#> 
#> A BibTeX entry for LaTeX users is
#> 
#>   @Manual{,
#>     title = {rmarkdown: Dynamic Documents for R},
#>     author = {JJ Allaire and Yihui Xie and Christophe Dervieux and Jonathan McPherson and Javier Luraschi and Kevin Ushey and Aron Atkins and Hadley Wickham and Joe Cheng and Winston Chang and Richard Iannone},
#>     year = {2025},
#>     note = {R package version 2.30},
#>     url = {https://github.com/rstudio/rmarkdown},
#>   }

Back to Table 1.

references

This key is extracted from the CITATION file if several references are provided. The first citation is considered as the preferred-citation and the rest of them as "references". It also extracts the package dependencies and adds those to this fields using citation(auto = TRUE) on each dependency.

Example 
cffobj <- cff_create("rmarkdown")

cffobj$references
#> - type: book
#>   title: 'R Markdown: The Definitive Guide'
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Allaire
#>     given-names: J.J.
#>   - family-names: Grolemund
#>     given-names: Garrett
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2018'
#>   isbn: '9781138359338'
#>   url: https://bookdown.org/yihui/rmarkdown
#> - type: book
#>   title: R Markdown Cookbook
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>   - family-names: Dervieux
#>     given-names: Christophe
#>   - family-names: Riederer
#>     given-names: Emily
#>   publisher:
#>     name: Chapman and Hall/CRC
#>     address: Boca Raton, Florida
#>   year: '2020'
#>   isbn: '9780367563837'
#>   url: https://bookdown.org/yihui/rmarkdown-cookbook
#> - type: software
#>   title: 'R: A Language and Environment for Statistical Computing'
#>   notes: Depends
#>   url: https://www.R-project.org/
#>   authors:
#>   - name: R Core Team
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     address: Vienna, Austria
#>   year: '2026'
#>   version: '>= 3.0'
#> - type: software
#>   title: bslib
#>   abstract: 'bslib: Custom ''Bootstrap'' ''Sass'' Themes for ''shiny'' and ''rmarkdown'''
#>   notes: Imports
#>   url: https://rstudio.github.io/bslib/
#>   repository: https://CRAN.R-project.org/package=bslib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Aden-Buie
#>     given-names: Garrick
#>     email: garrick@posit.co
#>     orcid: https://orcid.org/0000-0002-7111-0077
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.bslib
#>   version: '>= 0.2.5.1'
#> - type: software
#>   title: evaluate
#>   abstract: 'evaluate: Parsing and Evaluation Tools that Provide More Details than
#>     the Default'
#>   notes: Imports
#>   url: https://evaluate.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=evaluate
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Xie
#>     given-names: Yihui
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.evaluate
#>   version: '>= 0.13'
#> - type: software
#>   title: fontawesome
#>   abstract: 'fontawesome: Easily Work with ''Font Awesome'' Icons'
#>   notes: Imports
#>   url: https://rstudio.github.io/fontawesome/
#>   repository: https://CRAN.R-project.org/package=fontawesome
#>   authors:
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@posit.co
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.fontawesome
#>   version: '>= 0.5.0'
#> - type: software
#>   title: htmltools
#>   abstract: 'htmltools: Tools for HTML'
#>   notes: Imports
#>   url: https://rstudio.github.io/htmltools/
#>   repository: https://CRAN.R-project.org/package=htmltools
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@posit.co
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>     orcid: https://orcid.org/0000-0002-1576-2126
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: yihui@posit.co
#>   - family-names: Allen
#>     given-names: Jeff
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.htmltools
#>   version: '>= 0.5.1'
#> - type: software
#>   title: jquerylib
#>   abstract: 'jquerylib: Obtain ''jQuery'' as an HTML Dependency Object'
#>   notes: Imports
#>   repository: https://CRAN.R-project.org/package=jquerylib
#>   authors:
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@rstudio.com
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@rstudio.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jquerylib
#> - type: software
#>   title: jsonlite
#>   abstract: 'jsonlite: A Simple and Robust JSON Parser and Generator for R'
#>   notes: Imports
#>   url: https://jeroen.r-universe.dev/jsonlite
#>   repository: https://CRAN.R-project.org/package=jsonlite
#>   authors:
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>     orcid: https://orcid.org/0000-0002-4035-0289
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.jsonlite
#> - type: software
#>   title: knitr
#>   abstract: 'knitr: A General-Purpose Package for Dynamic Report Generation in R'
#>   notes: Imports
#>   url: https://yihui.org/knitr/
#>   repository: https://CRAN.R-project.org/package=knitr
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.knitr
#>   version: '>= 1.43'
#> - type: software
#>   title: methods
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     address: Vienna, Austria
#>   year: '2026'
#> - type: software
#>   title: tinytex
#>   abstract: 'tinytex: Helper Functions to Install and Maintain TeX Live, and Compile
#>     LaTeX Documents'
#>   notes: Imports
#>   url: https://github.com/rstudio/tinytex
#>   repository: https://CRAN.R-project.org/package=tinytex
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.tinytex
#>   version: '>= 0.31'
#> - type: software
#>   title: tools
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     address: Vienna, Austria
#>   year: '2026'
#> - type: software
#>   title: utils
#>   abstract: 'R: A Language and Environment for Statistical Computing'
#>   notes: Imports
#>   authors:
#>   - name: R Core Team
#>   institution:
#>     name: R Foundation for Statistical Computing
#>     address: Vienna, Austria
#>   year: '2026'
#> - type: software
#>   title: xfun
#>   abstract: 'xfun: Supporting Functions for Packages Maintained by ''Yihui Xie'''
#>   notes: Imports
#>   url: https://github.com/yihui/xfun
#>   repository: https://CRAN.R-project.org/package=xfun
#>   authors:
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: xie@yihui.name
#>     orcid: https://orcid.org/0000-0003-0645-5666
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xfun
#>   version: '>= 0.36'
#> - type: software
#>   title: yaml
#>   abstract: 'yaml: Methods to Convert R Data to YAML and Back'
#>   notes: Imports
#>   url: https://yaml.r-lib.org
#>   repository: https://CRAN.R-project.org/package=yaml
#>   authors:
#>   - family-names: Stephens
#>     given-names: Jeremy
#>   - family-names: Simonov
#>     given-names: Kirill
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.yaml
#>   version: '>= 2.1.19'
#> - type: software
#>   title: digest
#>   abstract: 'digest: Create Compact Hash Digests of R Objects'
#>   notes: Suggests
#>   url: https://eddelbuettel.github.io/digest/
#>   repository: https://CRAN.R-project.org/package=digest
#>   authors:
#>   - family-names: Eddelbuettel
#>     given-names: Dirk
#>     email: edd@debian.org
#>     orcid: https://orcid.org/0000-0001-6419-907X
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.digest
#> - type: software
#>   title: fs
#>   abstract: 'fs: Cross-Platform File System Operations Based on ''libuv'''
#>   notes: Suggests
#>   url: https://fs.r-lib.org
#>   repository: https://CRAN.R-project.org/package=fs
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Csárdi
#>     given-names: Gábor
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.fs
#> - type: software
#>   title: rsconnect
#>   abstract: 'rsconnect: Deploy Docs, Apps, and APIs to ''Posit Connect'', ''shinyapps.io'',
#>     and ''RPubs'''
#>   notes: Suggests
#>   url: https://rstudio.github.io/rsconnect/
#>   repository: https://CRAN.R-project.org/package=rsconnect
#>   authors:
#>   - family-names: Atkins
#>     given-names: Aron
#>     email: aron@posit.co
#>   - family-names: Allen
#>     given-names: Toph
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: McPherson
#>     given-names: Jonathan
#>   - family-names: Allaire
#>     given-names: JJ
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.rsconnect
#> - type: software
#>   title: downlit
#>   abstract: 'downlit: Syntax Highlighting and Automatic Linking'
#>   notes: Suggests
#>   url: https://downlit.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=downlit
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.downlit
#>   version: '>= 0.4.0'
#> - type: software
#>   title: sass
#>   abstract: 'sass: Syntactically Awesome Style Sheets (''Sass'')'
#>   notes: Suggests
#>   url: https://rstudio.github.io/sass/
#>   repository: https://CRAN.R-project.org/package=sass
#>   authors:
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@rstudio.com
#>   - family-names: Mastny
#>     given-names: Timothy
#>     email: tim.mastny@gmail.com
#>   - family-names: Iannone
#>     given-names: Richard
#>     email: rich@rstudio.com
#>     orcid: https://orcid.org/0000-0003-3925-190X
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@rstudio.com
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@rstudio.com
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.sass
#>   version: '>= 0.4.0'
#> - type: software
#>   title: shiny
#>   abstract: 'shiny: Web Application Framework for R'
#>   notes: Suggests
#>   url: https://shiny.posit.co/
#>   repository: https://CRAN.R-project.org/package=shiny
#>   authors:
#>   - family-names: Chang
#>     given-names: Winston
#>     email: winston@posit.co
#>     orcid: https://orcid.org/0000-0002-1576-2126
#>   - family-names: Cheng
#>     given-names: Joe
#>     email: joe@posit.co
#>   - family-names: Allaire
#>     given-names: JJ
#>     email: jj@posit.co
#>   - family-names: Sievert
#>     given-names: Carson
#>     email: carson@posit.co
#>     orcid: https://orcid.org/0000-0002-4958-2844
#>   - family-names: Schloerke
#>     given-names: Barret
#>     email: barret@posit.co
#>     orcid: https://orcid.org/0000-0001-9986-114X
#>   - family-names: Aden-Buie
#>     given-names: Garrick
#>     email: garrick@adenbuie.com
#>     orcid: https://orcid.org/0000-0002-7111-0077
#>   - family-names: Xie
#>     given-names: Yihui
#>     email: yihui@posit.co
#>   - family-names: Allen
#>     given-names: Jeff
#>   - family-names: McPherson
#>     given-names: Jonathan
#>     email: jonathan@posit.co
#>   - family-names: Dipert
#>     given-names: Alan
#>   - family-names: Borges
#>     given-names: Barbara
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.shiny
#>   version: '>= 1.6.0'
#> - type: software
#>   title: testthat
#>   abstract: 'testthat: Unit Testing for R'
#>   notes: Suggests
#>   url: https://testthat.r-lib.org
#>   repository: https://CRAN.R-project.org/package=testthat
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.testthat
#>   version: '>= 3.0.3'
#> - type: software
#>   title: tibble
#>   abstract: 'tibble: Simple Data Frames'
#>   notes: Suggests
#>   url: https://tibble.tidyverse.org/
#>   repository: https://CRAN.R-project.org/package=tibble
#>   authors:
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: kirill@cynkra.com
#>     orcid: https://orcid.org/0000-0002-1416-3412
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@rstudio.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.tibble
#> - type: software
#>   title: vctrs
#>   abstract: 'vctrs: Vector Helpers'
#>   notes: Suggests
#>   url: https://vctrs.r-lib.org/
#>   repository: https://CRAN.R-project.org/package=vctrs
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Vaughan
#>     given-names: Davis
#>     email: davis@posit.co
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.vctrs
#> - type: software
#>   title: withr
#>   abstract: 'withr: Run Code ''With'' Temporarily Modified Global State'
#>   notes: Suggests
#>   url: https://withr.r-lib.org
#>   repository: https://CRAN.R-project.org/package=withr
#>   authors:
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Henry
#>     given-names: Lionel
#>     email: lionel@posit.co
#>   - family-names: Müller
#>     given-names: Kirill
#>     email: krlmlr+r@mailbox.org
#>   - family-names: Ushey
#>     given-names: Kevin
#>     email: kevinushey@gmail.com
#>   - family-names: Wickham
#>     given-names: Hadley
#>     email: hadley@posit.co
#>   - family-names: Chang
#>     given-names: Winston
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.withr
#>   version: '>= 2.4.2'
#> - type: software
#>   title: xml2
#>   abstract: 'xml2: Parse XML'
#>   notes: Suggests
#>   url: https://xml2.r-lib.org
#>   repository: https://CRAN.R-project.org/package=xml2
#>   authors:
#>   - family-names: Wickham
#>     given-names: Hadley
#>   - family-names: Hester
#>     given-names: Jim
#>   - family-names: Ooms
#>     given-names: Jeroen
#>     email: jeroenooms@gmail.com
#>   year: '2026'
#>   doi: 10.32614/CRAN.package.xml2

citation("rmarkdown")[-1]
#> Xie Y, Allaire J, Grolemund G (2018). _R Markdown: The Definitive
#> Guide_. Chapman and Hall/CRC, Boca Raton, Florida. ISBN 9781138359338,
#> <https://bookdown.org/yihui/rmarkdown>.
#> 
#> Xie Y, Dervieux C, Riederer E (2020). _R Markdown Cookbook_. Chapman
#> and Hall/CRC, Boca Raton, Florida. ISBN 9780367563837,
#> <https://bookdown.org/yihui/rmarkdown-cookbook>.
#> 
#> To see these entries in BibTeX format, use 'print(<citation>,
#> bibtex=TRUE)', 'toBibtex(.)', or set
#> 'options(citation.bibtex.max=999)'.

Back to Table 1.

repository

This key is extracted from the "Repository" field of the DESCRIPTION file. Usually, this field is auto-populated when a package is hosted on a repository (like CRAN or the r-universe). For packages without this field on the DESCRIPTION (which is the typical case for an in-development package), cffr would try to search the package on any of the default repositories specified on options("repos").

In the case of Bioconductor packages, those are identified if a “biocViews” is present on the DESCRIPTION file.

If cffr detects that the package is available on CRAN, it returns the canonical URL form of the package (i.e. https://CRAN.R-project.org/package=jsonlite).

Example 
# Installed package

inst <- cff_create("jsonlite")

cat(inst$repository)
#> https://CRAN.R-project.org/package=jsonlite

# Demo file downloaded from the r-universe

runiv <- system.file("examples/DESCRIPTION_r_universe", package = "cffr")
runiv_cff <- cff_create(runiv)

cat(runiv_cff$repository)
#> https://ropensci.r-universe.dev

desc::desc(runiv)$get("Repository")
#>                        Repository 
#> "https://ropensci.r-universe.dev"

# For in development package

norepo <- system.file("examples/DESCRIPTION_basic", package = "cffr")

# No repo
norepo_cff <- cff_create(norepo)

cat(norepo_cff[["repository"]])

# Change the name to a known package on CRAN: ggplot2

tmp <- tempfile("DESCRIPTION")
file.copy(norepo, tmp)
#> [1] TRUE

# Change name
desc::desc_set("Package", "ggplot2", file = tmp)
#> Type: Package
#> Package: ggplot2
#> Title: A Basic Description
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: A very basic description. Should parse without problems.
#> License: GPL-3
#> URL: https://github.com/basic/package, https://basic.github.io/package
#> BugReports: https://github.com/basic/package/issues
#> Encoding: UTF-8
#> LazyData: true
#> RoxygenNote: 6.0.1.9000

cat(cff_create(tmp)[["repository"]])
#> https://CRAN.R-project.org/package=ggplot2

Back to Table 1.

repository-artifact

This key is not extracted from the metadata of the package. See the description on the Guide to CFF schema v1.2.0.

Back to Table 1.

repository-code

This key is extracted from the "BugReports" or "URL" fields on the DESCRIPTION file. cffr tries to identify the url of the source on the following repositories:

Example 
# Installed package on GitHub

cat(cff_create("jsonlite")$`repository-code`)
#> https://github.com/jeroen/jsonlite

# GitLab

gitlab <- system.file("examples/DESCRIPTION_gitlab", package = "cffr")

cat(cff_create(gitlab)$`repository-code`)
#> https://gitlab.com/ninijay/methoden

# Codeberg
codeberg <- system.file("examples/DESCRIPTION_codeberg", package = "cffr")

cat(cff_create(codeberg)$`repository-code`)
#> https://codeberg.org/dgkf/options

Back to Table 1.

title

This key is extracted from the "Description" field of the DESCRIPTION file.

title <- paste0("NAME_OF_THE_PACKAGE", ": ", "TITLE_OF_THE_PACKAGE")
Example 
# Installed package

cat(cff_create("testthat")$title)
#> testthat: Unit Testing for R

Back to Table 1.

type

Fixed value equal to "software". The other possible value is "dataset". See the description on the Guide to CFF schema v1.2.0.

Back to Table 1.

url

This key is extracted from the "BugReports" or "URL" fields on the DESCRIPTION file. It corresponds to the first url that is different to repository-code.

Example 
# Many urls
manyurls <- system.file("examples/DESCRIPTION_many_urls", package = "cffr")

cat(cff_create(manyurls)$url)
#> https://test.github.io/package/

# Check

desc::desc(manyurls)
#> Type: Package
#> Package: manyurls
#> Title: A lot of urls
#> Version: 0.1.6
#> Authors@R (parsed):
#>     * Marc Basic <marcbasic@gmail.com> [aut, cre, cph]
#> Description: This package has many urls. Specifically, 1 Bug Reports and 6
#>     URLs. Expected is to have 1 repository-code, 1 url and 3 URLs, since
#>     there is 1 duplicate and 1 invalid url.
#> License: GPL-3
#> URL: https://github.com/test/package, https://test.github.io/package/,
#>     https://r-forge.r-project.org/projects/test/, http://google.ru,
#>     https://gitlab.com/r-packages/behaviorchange, this.is.not.an.url
#> BugReports: https://github.com/test/package/issues
#> Encoding: UTF-8

Back to Table 1.

version

This key is extracted from the "Version" field on the DESCRIPTION file.

# Should be (>= 3.0.0)
cat(cff_create("testthat")$version)
#> 3.3.2

Back to Table 1.

References

Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, Robert Haines, James Baker, Spencer Bliven, Egon Willighagen, David Pérez-Suárez, and Alexander Konovalov. 2021. “Citation File Format.” https://doi.org/10.5281/zenodo.5171937.