It's in the ComRef 1.85:
scudState scud
Operand types:
scud: Object
Type of returned value:
Number
Compatibility:
Version 1.28 required.
Description:
Current state of given Scud launcher. Following states are recognized: 0 - No activity, 1 - Launch preparation, 2 - Launch prepared, 3 - Ignition, 4 - Launched. Note: Non-integral values are used to indicate transition between states.
Example:
scudState scudOne>=4