There is a Help topic with instructions on how to create the cross section...
nothing easier than this.
Just create a ordered part file with one single extrusion.
This is important.
Not start with a sketch nor add any additional feature as rounds, chamfers, thinwalls etc.
Only one extrusion of Your desired profile.
Save it into Your frame library and use it in structure frame design.
So, why only one single extrusion?
You also can only create a single sketch, but I prefer to have a 3D preview when using those profiles and therefore I just use the protrusion.
There is another function You can use, but You must not use, and this is the "Add Frame Origin Point"
Using this You can define Your preferred origin point rather than the cross section center
"You need not use" would be grammatically correct. And I knew it was your unfamiliarity with all the subtleties of English. It's just that "must not" has quite a different meaning than "need not" so it could sow confusion in the minds of some readers.
no no, I say thanks a lot for correcting me by my wrong usage of words.
I'm aware about must and must not and the meaning of them or may and may not.
The problem was, that sometimes the brain stays German where the hand is trying to write English.
I apologize for my mistake and thank for Your help and correction
I think that it is good as well that I'm not aware of all my other errors in my posts but thanksfully would appreciate any assistance