Define Proposed Reference Time for Technical Completion

Referrence Date in PM Order:

The logic behind maintating the Referrence date in PM Order.Actuall while completing the PM Order system is proposing the referrence date but i am not clear for what this referrence date is ?

Current date is proposed as default for reference date unless some other value is specified in customizing.

> Maintenance and service processing > Maintenance and service orders > Functions and settings for order types > Define proposed reference time for technical completion

The following settings are valid:

blank = Current date, 

1 = Created on date,

2 = Basic start, 

3 = Basic finish date