Hi,
thanks so far. I didn't got the whole story but I can work with.
I read those articles at MS but there's something that I don't understand completely:
at
https://www.oreilly.com/library/view/microsoft-visio-2013/9783848330416/ch15s16.html is listed that these values (DirXY) are for dynamic connectors only and size doesn't matter. But it does as I experienced).
at
https://docs.microsoft.com/de-de/office/client-developer/visio/dirxa-cell-connection-points-section it is mentioned that these two values give a vector.
But there is no vector (aside from top, bottom, left or right).
the rare information there is really MS-like.

This gluing shapes (your circles Yacine) together is currently not in my focus.
Let's go to a specific problem:
I have a vertical line.
At the top of this line have a connection point.
Regardless of the values for DirX, DirY and type the connector goes to the left or to the right - just from where the connector comes. Only if the other end of this connection line is almost precisely over this line it goes upwards.
Even if I give 0 to x and a million to y (which is the mathematically correct way imho) it goes left or right.
It seems to be impossible to force the direction of a connector that this goes upwards first and after a (specific?) distance sidewards. (I use static connectors only - from connection
point to connection
point).
as a workaround I replaced these lines with rectangles (with a connection point in the upper middle) , set GlueType to 8 and this works. The funny thing is if I give 1 to DirY it goes downwards, at -1 upwards. What strange logic behind?
You see I have lots of fun here.
Thanks for any hint
cheers!