When n is not provided, the critical region blocks only other instances of itself, but no other critical regions. Critical regions may appear anywhere in a program. That is, they are not limited to parallel regions. It does not guarantee that this number of processors will actually be assigned. Globally specifies the maximum number of CPUs that a code can use effectively.
Parallel regions are combinations of redundant code blocks and partitioned code blocks.
The scope of a variable in a parallel region is either shared or private. Integer array that has no repeated values for the entire routine. The following examples show shared and private variables and arrays. A END DO A is a shared variable because it is a read-only variable. END DO V is shared because it is a read-only array.