W o r m h o l e s

Wormholes exist between nearest massive objects (such as Black Holes, Star Clusters, and massive Blue Giants)

Wormhole has entry only from Black Hole side, e.g. Wormhole between a Black Hole and and other massive object which is not a Black Hole (such as Star Cluster or massive Blue Giant) works only from the Black Hole to the other massive object

You don't have to use wormholes

In order to jump through Wormhole you have to enter into gravitation anomaly at velocity of light, so a Wormhole shines, the shining depends the source of light on other edge of a Wormhole

The speed & direction of exiting equal to speed & direction of entering

The Wormhole might be protected by minefields

Advanced technology allows build Black Gates, ship cannot jump through one Black Gate to another Black Gate, it can jump only to the nearest massive object

Example:

You may jump from Black Hole A to Black Hole B , and vice versa, because the nearest massive object for Black Hole A is Black Hole B

You may jump from Black Hole B to Star Cluster C , because Star Cluster C  is the nearest  massive object for Black Hole B, but not from Star Cluster C to Black Hole B

You may not jump from Star Cluster C to Star Cluster D , and vice versa

You may jump from Black Hole E to Black Hole F , and vice versa

You may not jump from Black Hole A to Black Hole F , and vice versa, because the nearest massive object for Black Hole A is Black Hole B, and the nearest massive object for Black Hole F is Black Hole E

You may jump from Black Hole F to Massive Blue Giant G , but not from Massive Blue Giant G to Black Hole F

You may not jump from Massive Blue Giant G to Massive Blue Giant H , and vice versa

You may not jump from Black Hole F to Red Giant I , because of lack of mass 

You may not jump from Black Hole A to Massive Blue Giant G , and vice versa, because the nearest massive object for Black Hole A is Black Hole B