Optional text used to differentiate messages with identical original text but
different meanings.
This field should usually be left undefined.
It should only be used when there exist 2 or more messages that have
identical original text but are used in very different ways, so that one
translation won't work for both.
For example, maybe "close" needs to be translated in one place as "to close
something" but in another as "these things are close to each other".
In such a case, you would specify clarifying text in the "meaning" field. It
is different from the "description" field in that "meaning" is used when
computing the unique message identifier, but "description" is not. Although
this field may be shown to translators, its primary function is just to
serve as a point of difference to disambiguate 2 otherwise identical
messages.