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+Vail implement nine (9) keyer modes!  In each mode, there are up to two (2) keys or paddles.
+
+## Straight / Cootie
+
+Both left and right paddles transmit for as long as you hold them down.
+
+## Bug
+
+Left paddle sends "dot" repeatedly while held, right paddle sends for as long as you hold it down.
+
+## Electric Bug (ElBug)
+
+Left paddle sends "dot", right paddle sends "dit". Whichever was pressed most recently repeats.
+
+## Single Dot
+
+Same as ElBug. If you press and release the left paddle while something is being transmitted, it sends a dit next.
+
+## Ultimatic
+
+Same as Single Dot. If you press and release the right paddle while something is being transmitted, it sends a dah next.
+
+## Plain Iambic
+
+Holding left sends dit repeatedly. Holding right sends dah repeatedly. Holding both alternates between dit and dah.
+
+## Iambic A
+
+Same as Plain Iambic. If you press and release either paddle while something is being transmitted, it sends what you pressed next.
+
+## Iambic B
+
+Same as ElBug. If any key is pressed at the moment a dit or dah begins transmitting, that key will transmit once. The key that gets to transmit alternates between dit and dah.
+
+## Keyahead
+
+Same as Ultimatic, but "remembers" as many keys as you press. If you are transmitting slow enough, you can enter in a Q before the first dah has finished.
+
+## Thank-You
+
+Vail's keyers were implemented based on the excellent descriptions in [All About Squeeze Keying](http://cq-cq.eu/DJ5IL_rt007.pdf) by DJ5IL. I am indebted to the author for writing such a lucid and helpful document: I was able to "fix" my iambic modes with no additional input beyond this PDF file!