The IFDEF statement consists of three arguments:
IFDEF (<"Tag name">, <Hidden When value if tag defined>, <Hidden When value if tag undefined>)
The first includes a variable tag name. If the variable tag is defined in the tag database at project compilation, the IFDEF statement is replaced in the Hidden When field by the second argument. If the variable tag is undefined, the Hidden When field will contain the third argument.
IFDEF("Bit_1", 0, 1)
In the above example, if Bit_1 is defined in the tag database, the value in the Hidden When field will be 0. If Bit_1 is undefined, the value will be 1. Since the object is hidden when the value is TRUE, the object will be hidden when BIT_1 is undefined (i.e. when the Hidden When field contains 1).
If the second argument is omitted, as in Example 2, the variable tag specified in the first argument is used. If Bit_2 is defined, therefore, the Hidden When field will contain Bit_2. The value of the variable tag Bit_2 is then used to determine if the object is hidden. A non-zero value will equate to TRUE, causing the object to be hidden.
If Bit_2 is undefined, the Hidden When expression evaluates to 1 (TRUE) and the object is hidden.
To enter an IFDEF statement in the Hidden When Field: