Descriptors Types Recommended / And Unique question

which means in practice “unique” for descriptors?

about the various types of descriptors = DE, SB, SP, HY, CO, PH
I could not find anything that says when each is recommended ?!

Unique means only one inverted list entry will be allowed for any specific descriptor value,
for example only one record with LastName=“Jones”.

Introduction to descriptor types

Thanks. i see.

In windows to create FDT

the field “DDM DC:”

What is this?

I don´t find in documentations.

Why don’t you just click the Help button on the FDT editor window ?

Sorry

I go to web documentation adabas and i don´t click this option.

I see now.

The descriptor with Unique Option
is the same as
a unique key in other databases like mysql?

I guess so. When I read http://en.wikipedia.org/wiki/Unique_key is sounds like a unique descriptors from an ADABAS point of view (although ADABAS is not a relational database)