The HOVER_HELP keyword displays a tooltip containing the help text for a property when the user moves the pointer over the property field in the edit session for a diagram, symbol or definition. It also shows the help string in the edit session status bar when the user clicks inside the property field.
Syntax
HOVER_HELP "text"
Example
PROPERTY "MyDescription" {EDIT TEXT LENGTH 1500 HOVER_HELP "This is my description field"}