Beckhoff BC9000 Documentation page 21

Fitting and wiring
STP
Shielded twisted pair
Describes a cable with an outer screen, without defining the nature of the screen any more closely.
S/STP
Screened/shielded twisted pair (wires are individually screened)
This identification refers to a cable with a screen for each of the two wires as well as an outer shield.
ITP
Industrial Twisted-Pair
The structure is similar to that of S/STP, but, in contrast to S/STP, it has only one pair of conductors.
BC9000 and BC9100 Version: 4.0.0 21