[Therion] "Passage height" question

[Bill Gee]

Hello everyone - I have a question about the point type "Passage height".  I 
am working on a map which has some ceiling heights under 1 foot.  When I put 
in "-value [0.5 ft]", for example, it comes out on the map as zero, or "-value 
[1.5 ft]" comes out as 2.  Is there a way to make those come out with the 
value given?

There is a passage section which has a voice and light connection, about 35 
feet long and 6 or 8 feet wide but only 6 inches high.  It is not human 
passable, but we can talk through it.  I want to indicate its height 
correctly.

Thanks - Bill Gee