[ale] LSM compatability module

[jtholmes]

I was having problems with  vsftpd working after login and accidentally 
read a post about loading the 'compatability module" loaded it and 
things started working fine.

I  know basically what 'compatability module' does but want some indepth 
info on it. I have searched the net high and low and can find virtually 
no info on it , short of reading the code and decyphering it I would 
like to see some indepth docs.

Can anyone point me in the right direction for information on 
'compatability module"?
thanks
jtholmes