To answer your first question, which is whether this is standard practice, it's not uncommon to see one section of the code referenced elsewhere in the code, but it's usually done so by making reference to the specific section, rather than by repeating the section. We see examples of that throughout the code.
With respect to your second question as to whether this would change anything for the board or the interpretation or definition of section 87.4, which is the section that authorizes the board, if the parties cannot agree, to make determinations as to what services must be maintained in the event of a strike or lockout, it's difficult to say how the board would interpret this new word that would appear in this clause vis-à-vis what it's told to interpret in section 87.4.
We do know that, based on the current section 87.4, in the cases that were put in front of it, notably Aliant and TELUS, which dealt with telecommunications, the board felt it had no evidence that those 911 services were essential and therefore did not make a declaration. But I'm unable to predict whether the addition of this word in a different section of the code would give the board different scope, and I defer to the legislative clerk on that.