I am trying to create auto-count equation numbers for my long thesis. The format being used for the equations in our university is "(chapter-number)". And then you will cross-reference as : Equation 3-20. I have used multilevel auto numbering to achieve that.

F = m.a (‎3-20)

The parenthesis I have used for the reference are interpreted as:

"(" as the label
")" as the caption text.

Now when I cross-reference I have these options (with the outcome of each option):

Entire caption : appears as -> (3-20) //has unwanted parenthesis
Only label and number : appears as -> (3-20 //unwanted opening parenthesis
Only caption text : appears as -> ) //only the closing parenthesis appears
Page number (unrelated)
Above/Below (unrelated)

If we had an "Only number" option my problem could be solved. How should I create the auto-number and how should I do the cross reference.

P.S: I don't have this problem with Figures, Tables, etc since the figure is references as "Figure 3-1: description" and cross referenced as "Figure 3-1", so I can easily use the "Only label and number" option. In the case of equations those parenthesis are bothering.

Regards