step7 reference data

Hi,

I understand how to cross reference, display data, filter etc, can anyone explain in simple terms all the applications of displaying reference data (what its used for etc..) and also Ive read in the siemens manuals that reference data can be found in 6 different lists; cross references, assignment of IQM, assignment of T/C, program structure, unused symbols, addresses without symbols.

I do have the necessary materials, but a simple explanation of why instead of just how would be very useful for a beginner like myself.
Thanks

Tom

______________-
You'll never walk alone

In short:

Cross reference:
Will list all used adresses and WHERE they are used.
The general purpose place to find out how (dis)organized your program is
Important note: If some adresses of different types are overlapping (M5.3 and MB5 and MW4 and MD2 for example), then this is the only place that I am aware of that lets you check this. And you have to do a lot of browsing up and down to do it.
If somebody knows an easier way I would be VERY glad to know about it.

Assignment of IQM:
Will list used Inputs, outputs and flags.
Great for finding places where to add new things to your program. You know: thats the UNUSED I, Q and M areas

Assignment of TC:
Will list used timers and counters.
Also great for finding places where to add new things to your program.

Program structure:
Will list which program subroutines calls which. Only helpful if you are REALLY confused

Unused symbols:
Will help you find those parts of your program you can get rid of.

Adresses without symbols:
Will help you find those parts of your program you forgot to comment properly.

Only for examble:
Do not use Libraty function FC82 (RSET) block, you can't see its referces !!!!