What is the use of OR and AND functions in counter based maint plan

Hi

I want to create a counter based maintenance plan...

I entered the measurement reading for the counter, reading is 4000 hrs

IN IP43

I created the counter plan with cycle as 6000 hrs. Once the document reaches 6000 order will be created. While creating the maintenance plan, in the maintenance schedule parameters, i check there is OR and AND functions avaliable...

I know the basic use of both the functions..

But what is the significance in the maintenance plan....

Will it give any effect, between the schedule date and measurement docu entries...

Since i need to maintain like... once the counter reaches 6000 hrs only order should be created.. it should not create once the date as been reached... since due to present condition, i am not running the DG....

Give ur inputs

- Pithan