Recently, I came across some useful diagrams and notes related to cabling.
Here are the urls:
Good technical articles at: www.internetcsi.com/edd.htm#technical
Useful: ftp.dgii.com/techsupport/hardware/cable/
For an incredible diagram showing RJxx to DBXX pinouts, see:
http://ftp.dgii.com/techsupport/hardware/cable/rjdb3.pdf
also: www.man.ac.uk/~mbhmivv/telecom.html
John Backus
www.beechglen.com