The DLM_REGISTER procedure registers a Dynamically Loadable Module (DLM) in IDL that was not registered when starting IDL. This allows you to create DLMs using the MAKE_DLL procedure and register them in your current session without having to exit and restart IDL.
Manually register and then call a routine within a DLM file that is not on !DLM_PATH:
; later on, we call a routine within the mycode DLM
MYROUTINE, a, b, c
% Loaded DLM: MYCODE.
DLM_REGISTER, File1 [, File2, ..., Filen]
The full path to the DLM module definition file to read.