Is there a command something like \NeedsTeXFormatAtLeast{LaTeX2e}[date]

Question

I know about the command \NeedsTeXFormat, as in such as \NeedsTeXFormat{LaTeX2e}[2023/11/01]. But:

does this automatically allow a later LaTeX format to be used?
if not, is there some similar command to specify to use a LaTeX format at least as new as the specified date?

@DavidCarlisle: thanks for the edit. I was looking for something appropriate, which your edit gives as latex-base. — murray
– murray, Commented Jan 29, 2024 at 19:25

egreg · Accepted Answer · 2024-01-29 17:40:57Z

Any format released after the specified date is accepted. An earlier release date issues a warning.

Consider the file

\NeedsTeXFormat{LaTeX2e}[2023/11/01] \showthe\fmtversion \stop

No problem at all and I get

> \fmtversion=macro: ->2023-11-01.

Let's fake being after the next release, which will be dated 2024-05-31 (or thereabout):

\def\fmtversion{2024/05/31} \NeedsTeXFormat{LaTeX2e}[2023/11/01] \show\fmtversion \stop

No problem at all and I get

> \fmtversion=macro: ->2024/05/31.

Note that \NeedsTeXFormat will look at the meaning of \fmtversion and nothing else. Indeed if I fake having an earlier release

\def\fmtversion{2023/05/31} \NeedsTeXFormat{LaTeX2e}[2023/11/01] \show\fmtversion \stop

the LaTeX run issues

LaTeX Warning: You have requested release `2023/11/01' of LaTeX, but only release `2023/05/31' is available. > \fmtversion=macro: ->2023/05/31.

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