[Therion] Underscore coming out as period in legend comment

[Andrew Atkinson]

When using

map-comment

if you put an underscore in it comes out as as period (.)

I am trying to include a web address that includes underscore.

Metapost tells me that \textunderscore or \_

but that only works in metapost /comment, which is a bit of a pain, and
not in map-comment directly.

Is there a way of using it directly in map-comment?

thanks

Andrew