Indexed/Unique IDs

[ID015]

I am collecting requirements in Word (I know, other tools would be better but...) and they need to have a unique ID and I need some ideas or suggestions to automate the keeping of unique IDs.

The document will be structured like:
Heading: Requirement Name (ID01)
Paragraph: Table

When I add a new requirement (consisting of a heading and table) I would like the heading to be ID02, then ID03, etc

The adding of the new requirement will be called from custom code.