zones have models loaded by default, in the s3d file, txt make it possible to add models after, for revamp or special events I think, so you have the regular zone mobs in s3d, but s3d files calls for a "zonename_chr.txt"
Even if a zone don't have a _chr.txt file, you can create one, I did this with Kurn that had no txt file, created one and it works just fine
And do to do it in 5 mins, check the mobs you want in the EQemu pdf, check numbers (or directly the xxx,xxx_chr sometimes)
Check the thread about models on this forum if the model name.txt is found already
if not try to figure it out
Edit your eq directory
Play
If you made an error just do as if they were loaded correctly, scribe it somewhere so you don't forget, and fix later..
EDIT: btw aye btn is probably bats, from newbie zone, rtn is also rats probably