swaps illustration diagrams -- how to read

This write-up covers IRS, x-ccy swap...

These block diagrams are popular and partially useful, but beginners often don't realize:

* initial context -- typically a corporation has a periodic liability, or an investor has a periodic income.
** We had better ignore all the other arrows first.

* the motivation -- typically to convert the initial single arrow to other arrows. The swap contract adds 2 arrows, one of them cancelling out the pre-existing arrow.
** we had better focus on the 3 arrows and ignore other parts of the diagram.