Help me understand seamark light patterns.

It's not clear to me how the seamark:light:character tags work in conjunction with the seamark:light:period and seamark:light:group tags. To be specific, I'm trying to parse the seamarks, not add new ones.

These are the sources which I'm using:
http://wiki.openstreetmap.org/wiki/Seamarks/Lights
http://wiki.openstreetmap.org/wiki/Seamarks/Light_Characters (when I mention examples, they are on this page)
http://wiki.openstreetmap.org/wiki/Seamarks/INT-1_Section_P
https://en.wikipedia.org/wiki/Light_characteristic

1: Does the various types of flashes (flashes (Fl), quick flashes (Q), very quick flashes (VQ), ultra quick flashes (UQ) long flashes (LFl), isophases (Iso) and occults (Oc)) have a standard length for when a period isn't listed? Also, what about the length of darkness between the flashes? This seems to matter since in example 8 three flashes are grouped together and the long period causes a long pause rather than spreading out the flashes evenly. All I can find is the maximum and minimum frequency of quick, very quick and ultra quick flashes and the minimum length of long flashes.

2: Why does example 18 have a long pause? They don't mention any grouping here. Shouldn't that be interrupted ultra quick flashing (IUQ) rather than just ultra quick flashing (UQ)? How do I know how long the pause should be in an interrupted flashing if there's no grouping and/or I don't know how long each flash is?

3: Seeing from examples 25, 26 and 27 it seems that flashes have standard lengths that each grouping adhere to internally, but if there are multiple groupings then those are spread out evenly over the period. Is this correct?

4: The examples on the Light Characters page are numbered, but some numbers are missing. Can I find more of these examples somewhere?

You don't have to answer all of these questions. If you can only answer one of them I will still appreciate it.