Where is there a key to the different redstone circuit notations used on the minecraft wiki?

There are lots of schematics of minecraft circuits online, but few of them reference the notation they are using and I am finding it hard to chase down what some symbols mean.

The page on Advanced Redstone Circuits references the MCRedstoneSim format. The most recent version of that is 13 January 2013. It does not contain symbols used on many minecraft schematics.

For example Layer 0 of a shift register here:

http://www.minecraftforum.net/forums/minecraft-discussion/redstone-discussion-and/342872-grizdales-shift-register

has squares with grey and red/grey triangles in them. I have no idea what they are supposed to be.

On the wiki itself there are weird triangular things as well, for instance a diagram of an edge detector (http://minecraft.gamepedia.com/Pulse_circuit#Edge_detector) has things I don't understand in it.

Is there a reference for these notations somewhere? (I am trying to make a simple 2 bit shift register as it happens).

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Squares with grey and red/grey triangles in them

These represent Redstone Repeaters.

The direction that the arrow points indicates the direction of the repeater's input/output, with the input being the flat end and the output being the pointy end.

You may notice that the triangle has four 'tiers', with each tier being either red or grey. Redstone Repeaters have four tick delay settings, so the more red tiers there are, the longer the tick delay setting:

That indicates a Redstone Repeater with a 1 tick delay outputting to the east, whereas this:

Indicates a 3 tick delay Redstone Repeater outputting to the east.

How light or dark the red is indicates whether the repeater has a redstone current in its idle state. The two examples above both indicate that the repeater has no redstone current when idle, whereas this:

Indicates a 4 tick delay repeater that outputs to the south and is receiving a redstone current in its idle state.

The same rules apply for yellow and grey backgrounds as for everything else so I won't cover those.

Personally I find this style of repeater easier to read at a glance than the current 'official' way of indicating a redstone repeater, which is like so:

Which would be a 1 tick delay active repeater outputting to the east.

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Is the "official" usage documented anywhere? I find it baffling there's no obvious key. – Francis Davey Aug 24 '14 at 11:43
It's in the image of the MCRedstoneSim format that you linked to in your question, 12th icon along – JonK Aug 24 '14 at 11:45
Oh yes - I missed that. I was looking for the triangles. – Francis Davey Aug 24 '14 at 11:50