prevent line break within citation in PDF output

[ietf-svn-bot]

type_defect | by arusso@amsl.com

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In PDF output, it should keep together an xref's target, i.e., prevent a line break in the string of citation. Example: there's a line break in "[BT.709-6]" after the period; screenshot attached. In context, it's on page 18 of RFC 9134 (https://www.rfc-editor.org/rfc/rfc9134.pdf) - it's the PDF rendering of an <xref> in a <t> in a <dd>. Using v3.10.0.

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Issue migrated from trac:685 at 2022-02-08 07:18:05 +0000

[ietf-svn-bot]

@arusso@amsl.com uploaded file linebreak.png (76.8 KiB)

[alicerusso]

Another example of this issue. The undesired line break appears within [G.9959] in this PDF (page 4).

https://www.rfc-editor.org/v3test/test9453.pdf
https://www.rfc-editor.org/v3test/test9453.xml (source)

[cabo]

What should the rules for line-breaking/hyphenation of xrefs be? There are many ugly long anchors that clearly need to be line-broken, so where should it stop? Breaking off three characters is not very nice, but [BT. are four characters...
Should it be possible to manually mark an anchor as non-breaking, so this can be done as a tweak?
(The tweak could be in bib.ietf.org.)

[lbartholomew-rpc]

This issue also occurs in tables (e.g., see the latter portion of Table 1 on https://www.rfc-editor.org/authors/rfc9423.pdf). The fix needs to be universal (i.e., no breaks in citation strings within paragraph, list, or table markers).

[ajeanmahoney]

There is an RFC in TI state waiting on this issue (not urgent, though, as the IANA registry is already set up):
https://mailarchive.ietf.org/arch/msg/auth48archive/_keJFlsF6PkzqNg7LeVq4CIi-eE/