The 3 per side open ended straight draw rule

This is for NLH, but it may apply to other variations of poker.

If there are two cards of adjacent rank on the board, then the 3 ranks below and the 3 ranks above can complete an open ended straight draw. For example, if the board is:

6s7cKd

then a 3, 4, 5, 8, 9 or 10 can complete an open ended straight draw.