posted by Jamie .
If you have a parallelagram ABCD, and line segment AB is on the left, can you read it as BA as well or is that backwards?
Of if the alphabetical order was different and it was parallelagram PGAD, would you still only be able to read it as line segment PG or could it be GP as well?
Both versions indicate the same line, but it just makes it simpler to use the original order. If you were using it to indicate lines of travel, then it would make a significant difference.