Hi again, wdmc.
I just had a look at the Blackbird tab, and as it turns out, it's a great example to use.
Here it is again:
From the top: the vertical lines with the
red numbers above indicate the bars, the measures, which is a time-line thing. This tune is unusual in that the time signature changes. The first is a 3/4 measure, then it changes to 4/4. You can easily see the three beats in that bar. They are quarter beats and have a vertical line that goes up through the notes. So 3/4 means three quarter beats per bar.
The second bar is in 4/4, so there must be the equivalent of 4 quarter beats there ... exactly. The first cluster is a quarter beat, like those in bar 1. They have the same vertical line that goes right up through them. Then comes the two eighth beats ... they're joined below by the horizontal line. So you need two of them per beat. The next pair of notes have a shorter vertical line below them. That beat is a half beat ... 2 quarters.
Next bar (
3) is simply 4 quarter beats; next (
4) is two half beats ... and on it goes. Each measure, or bar, must equal 1. The very last chord has nothing underneath ... it's a whole tone ... one whole beat.
So that's how the vertical lines work:
No line = whole beat
Short line = half beat
Long line = quarter beat
Long lines connected by one horizontal = eight beat
Long line connected by two horizontal = sixteenth beat
Above the tab are chord symbols. Here, you're looking at the fretboard of a guitar, held upright. If there are two small horizontal lines at the top of the grid (underneath the x's and o's) then you're looking at top of the fretboard. Those two lines represent the nut. If it's further up the neck, the tiny number shows what fret that is ... the third chord has a tiny '10' next to it. That means that is the 10th fret. Some of the other numbers are a little squashed, but mean the same thing.
So the top grid-like symbols are the guitar neck in a vertical position. I sometimes add open strings to those chord symbols, to show the shapes that I'm working around, so the little symbols don't always match the tab below. Once you get a bit more familiar with guitar playing, you'll see why I do that.
The vertical lines show the timing. It's often said that tab is not useful becasue it doesn't indicate the timing, but no more.
GuitarPro does a pretty good job of that.
As for the same chord looking different ... chords are just a selection of notes, 3 minimum, and those notes are found in multiple positions, so therefore there are multiple configuartions for any one chord.
I will do the tab lesson though.