11.4.3 @itemx

Use the @itemx command inside a table when you have two or more first column entries for the same item, each of which should appear on a line of its own.

Use @item for the first entry, and @itemx for all subsequent entries; @itemx must always follow an @item command, with no blank line intervening.

The @itemx command works exactly like @item except that it does not generate extra vertical space above the first column text. If you have multiple consecutive @itemx commands, do not insert any blank lines between them.

For example,

@table @code
@item upcase
@itemx downcase
These two functions accept a character or a string as
argument, and return the corresponding upper case (lower
case) character or string.
@end table

This produces:

upcase

downcase

These two functions accept a character or a string as argument, and return the corresponding upper case (lower case) character or string.

(Note also that this example illustrates multi-line supporting text in a two-column table.)