Move a line segment

Assuming a default PCB Editor installation in General Edit Application Model, hover over the item, right-click>Move, then left-click in the PCB Editor Command Window and type "x <xLocation> <yLocation>" like "x 20 50" to place at x=20 and y=50, Command needs a lower case x and spaces between the parameters, press enter to accept the command.

Ok but I in this way I specify only one set of coordinates and I don't know at what point in the segment the coordinates are associated. Is there a way to move both the edges of segment and so specify two set of coordinates? 

With 'line' element in find filter, hover over the line; RMB (snap -> to segment center) and it should select the midpoint of the segment. Then do like Oldmouldy mentioned. Once you master the 'snap' function of Allegro, you'll be a amazed what you can do.

You can also do the same with the line's vertex. Hover over the line's endpoints and 'snap -> to segment vertex  and with coordinates you can move them precisely where you desire.

After RMB I don't see the snap option 

After RMB I don't see the snap option 

Darn. I trying to think through the steps outside Allegro. Sorry. Try this - Filter: Other segments - hover over the end of the line and RMB move. It will select the vertex. Then do the 'x', 'y' or 'ix/iy' move. It will move the segments accordingly.

Ok now it works but if I wanted to move only one vertex mantaining the other one in the same position how could I do? In other words I want to change the originale segment length

See my previous step. Use the vertex as the movement selection. This will move one end or the other, not the whole line.

I select the vertex then RMB->move, 'x' 'y' , but it moves all the segment maintaining the length