ITP and ITP Height

In the pictures below, means that no ITP is required; means an ITP is required.
In the case below, the number of plies is defined by the adjacent zones.
No ITP is required:

In the case below, the number of plies is undefined, an ITP is required.
In this case, the stack is an exact multiple of plies thickness.
The ITP can be an integer (see command ITP):

In the case below, the number of plies is undefined, an ITP is required.
In this case, the stack is not an exact multiple of plies thickness. 
The ITP cannot be an integer. An ITP Height is required.