Oracle Documentation

Oracle provides documentation on several locations:

official documentation page
Oracle Technology Network
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My Oracle Support
for users with a support contract. A support identifier (SID) is needed to create a login.
OTN Community Forums

Internal documents are called Notes and identified by a number. You can find them on Metalink, but if you don't have access you can search the forums, as many are posted there by the support staff.

General Documentation

Oracle Intelligent Agent User's Guide, Release 9.2.0.2 ,2002-10
Chapter 3 discusses Tcl and OraTcl.
Oracle® Warehouse Builder API and Scripting Reference 11g Release (11.1)
Describes the use of Tcl with Warehouse Builder

Oracle Notes relevant for Tcl

Note:69597.1
Overview of the Job TCL Files Used by the Intelligent Agent (16-APR- 1999 - 15-APR- 2002) [1 ]
Note:69563.1
Overview of the Event TCL Files Used by the Intelligent Agent (15-APR- 1999 - 15-APR- 2002) [2 ]
Note:69598.1
Overview of the Miscellaneous TCL Files Used by the Intelligent Agent (16-APR- 1999 - 15-APR- 2002) htt//metalink.oracle.com/metalink/plsql/showdoc?db=NOT&id=69598.1
Note:62463.1
Detailed Guide on How the Intelligent Agent Works (04-SEP-1998 - 12-APR-2002) [3 ]
Note:1017043.6
WHAT ARE THE ORATCL EXTENSIONS USED FOR TCL SCRIPTS? (08-APR-1996 - 16-DEC-1996) [4 ]
Note:115961.1
Logging and Tracing the Intelligent Agent (26-JUL-2000 - 12-APR-2002) [5 ]
Note:1017042.6
HOW CAN I USE TCL AGENT SCRIPTS WITH ORACLE ENTERPRISE MANAGER? (08-APR- 1996 - 16-DEC- 1996) [6 ]

1996 ??? Must have been Tcl 7.4 or so.

How to set up an example user defined event :