[BlindMath] A UEB-Related Query: Sec. 10.6.1 in the Rulebook

[Saaqib Mahmuud]

Hi mates?
I've a confusion about an example in Sec. 10.6.1 in the UEB Rulebook, 2nd edition 2013: 
The word "disturb" --- with the final four letters of the word to be in italics --- is to be transcribed. In the Rulebook example, the lower groupsign "dis" has not been used. However, I think the lower groupsign CAN be used. 
What is the correct thing to do?
Regards.
Saaqib