Is...

Visual basic

Isnothing
Return true if it is nothing

Isarray
Return true if it is an array

Isdate
Return true if it is date

IsDBNull

Iserror
Return true if it error

IsNumeric
Return true if it is a Numeric

IsReference
Return true if it is a reference

Microsoft built-in function
=Isblank
=Iserr
=Iserror
=Iseven
=IsLogical
=IsNA
=IsNontext
=IsNumber
=IsODD
=IsPMT
=Isref
=Istext