Expressions

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if(point("../resample3", 0, "N", 2)<0, 0, 1)

Menu expressions taken from Forum:

So you could do { parma == "" parmb == "" } this would mean they both need to be true in order to work an (and) operation. Or if { parma == "" } { parmb == "" } would be an (or) operation. You can also do ==, !=, <, >, >=, <=, =~ (matches pattern), !~ (doesn’t match pattern) as additional operations. What is a actually quite common is to make a parameter that is invisible (or under a hidewhen under an advanced set of options) that you can use to hide and disable parameter and folder menus.