The "unary-" operator in OCL (Object Constraint Language) is simply the negative sign you put in front of a number to make it negative. The term "unary" just means it acts on one value (unlike a "binary" operator like + or - that acts between two values).

Examples:

Expression:

-(3 + 2)

• Compute (3 + 2) = 5

• Unary minus makes it -5

Precedence:

Unary minus has higher precedence than addition or binary minus.

Example:

-3 + 2

• Interpreted as (-3) + 2 = -1

• Not as -(3 + 2)