time-stamp-conversion-warn

time-stamp-conversion-warn is a variable defined in `time-stamp.el'.
Its value is

t

Documentation:
Warn about soon-to-be-unsupported forms in `time-stamp-format'.
If nil, these warnings are disabled, which would be a bad idea!
You really need to update your files instead.

The new formats will work with old versions of Emacs.
New formats are being recommended now to allow `time-stamp-format'
to change in the future to be compatible with `format-time-string'.
The new forms being recommended now will continue to work then.