[Rd] Adding text comments to graphics device output files?

[Henrik Bengtsson]

Hi,

several image file format supports textual/meta data comments in one
way or the other.  For me an obvious usage would be to add
sessionInfo() information to PNG and PDF image files, ideally from
within R although external tools would work as well(*).  Has anyone
looked into this or have any suggestions or comments?

/Henrik

(*) One could even imagine including self-contained R
scripts/vignettes within such comments.