Variable might not have been initialized

This variable is read from, although it hasn't been initialized properly. Therefore, its value may be unpredictable. Example:

if real(#pixel) >= 0
  z = 1
endif
z = sqr(z)  ; z might not have been initialized

When the real part of #pixel is negative, no value is assigned to z. That means it can in fact have any value, and that is probably not what you intended. When the compiler generates this warning, the variable is initialized to 0, so it will never have a random value. But you should carefully check your code and initialize the variable to its proper initial value.

This is a possible solution to the example presented above:

if real(#pixel) >= 0
  z = 1
else
  z = 2
endif
z = sqr(z)  ; z is always initialized now

Note: For efficiency reasons, reads from array elements are not checked and arrays are not initialized to zero either. Reading from an uninitialized array element will return an unpredictable value without generating a warning.

See Also
Warnings