My model (cif format) contains 34 chains, and so I've been using upper case and lower case letters for chain IDs. When I read in my model, the select command distinguishes between upper case and lower case, but after applying the split command on my model ('split #1 chains'), the select command no longer distinguishes between upper and lower case. I.e. 'select #1/D' will select both chains D and d. The split command works correctly, producing models 1.1-1.34. 

Also, is it possible to create a model from a selection? I can't find such a command anywhere, and the only thing I can figure out is to do the following: 

'save name format mmcif models selecion_name; open test.cif'

Thanks, 

Yazan