Notation Conventions

Each message description contains:

Name

The message name; a 2-byte identity unique to a message.

Some message identity values are reserved for the use of the operating system, some are available for use by an application. See Reserved Messages under Default Window Procedure Message Processing.

For all messages, the first two or three characters of the name indicate the type of window that is related to the message; for example:

LM

List box control
SBM
Scroll bar control.
Cause
The principal reason that caused the generation of the message.
Parameters
Input and output parameters pertinent to the message.

There are always two parameters (param1 and param2) and one return value. Any or all of the parameters can be NULL.

Remarks
An explanation of the relationship between the parameters in the context of the message and an indication of the expected processing of the message.
Default
A definition of how the default window procedures (provided by the system) process the message.

Note: A message is not equivalent to a call of the same name.

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