Yes you can alter UIDs .. they were put in to fix some old bugs. Early versions of layouts did not have them. There is little reason to edit them manually. This is kind of a special case and the only reason to edit them is to let the Layout editor know they are not valid UIDs (I use negative numbers since real UIDs should never be negative). One thing to note .. the Layout editor Group tab works using UIDs.
Heh. Yeah. Ok. Was that the third or fourth decimal place that I changed last time? ((Changes a number.)) $#!+, wrong one...
Gah, been there, done that, just recently...had more Wispy Vampiric Mirrors than I thought and got confused as to which numbers were for E/W and N/S...really embarrassing, since I was the one that had brought Mistal's wonderful Notepad guide up to date and re-issued (thanks again, Mistal! )... Uwk