I can understand that altitudes may be "by ATC", but why can a route also be marked with "by ATC"? All SID routes need prior clearance by ATC, right?
For example, in SID RWY 16 for ZGSZ/SZX, MEPOG-7X and LKC-7X are "by ATC", while others are not. I know that LKC-7X is not a regular route flown, but still: what does "by ATC" mean here?