Problem: So I have ran across the following part and I simply don't know what it is. I tried searching for if you will a description of it. (I.E. two diodes on top of each other pointing opposite directions) This of course did not help.
Help: So what is this?

Advice: So when you run across something you don't know how do you solve this? I mean besides using context clues from the circuit. If its just a symbol and you can not identify the part. Advice?
Notes: It is from the block diagram of the datasheet of the MC14468.