The above diagrams convey nothing concerning the tuning used. When no tuning information is given (as in the above) then standard tuning is assumed. This is the form most tablature takes.
It can be desirable, however, to use non-standard tunings. To provide the tuning information a letter is included at the start of each string which represents it's tuning. Standard tuning, therefore, is:
e|-------- the top-most string is tuned to high E B|-------- the second-from-top string is tuned to B G|-------- the third-from top string is tuned to G D|-------- the third-from-bottom string is tuned to D A|-------- the second-from-bottom string is tuned to A E|-------- the bottom string is tuned to low E
As an example, for the intro/main riff of "Hey You" by Pink Floyd, I play with the fourth string tuned down to "F". This tuning is illustrated as follows:
e|-------- B|-------- F|-------- tuned down to "F" (usually tuned to "G") D|-------- A|-------- E|--------
