reftex-label-menu-flags

reftex-label-menu-flags is a variable defined in `reftex-vars.el'.
Its value is

(t t nil nil nil nil t nil)

Documentation:
List of flags governing the label menu makeup.
The flags are:

TABLE-OF-CONTENTS Show the labels embedded in a table of context.
SECTION-NUMBERS Include section numbers (like 4.1.3) in table of contents.
COUNTERS Show counters. This just numbers the labels in the menu.
NO-CONTEXT Non-nil means do NOT show the short context.
FOLLOW Follow full context in other window.
SHOW-COMMENTED Show labels from regions which are commented out.
MATCH-IN-TOC Obsolete flag.
SHOW FILES Show begin and end of included files.

Each of these flags can be set to t or nil, or to a string of type letters
indicating the label types for which it should be true. These strings work
like character classes in regular expressions. Thus, setting one of the
flags to "sf" makes the flag true for section and figure labels, nil
for everything else. Setting it to "^sf" makes it the other way round.
The available label types are: s (section), f (figure), t (table), i (item),
e (equation), n (footnote), plus any definitions in `reftex-label-alist'.

Most options can also be switched from the label menu itself - so if you
decide here to not have a table of contents in the label menu, you can still
get one interactively during selection from the label menu.

You can customize this variable.