Solo 4 starts off in the 3rd Blues Position and uses the Standard Riff in bar 1 in a different timing.

Start the solo with your pinky on the tonic and notice that it goes “over” the octave in bar 2.

The lick from bar 2 to 3 is a typical Charlie Christian lick.

The Standard Riff on the IV chord is slightly altered, emphasizing the 6th of the chord.

Notice how easily you can change from the 3rd Blues Position to playing the Standard Riff on the IV chord.
Move it up two frets and you’re on the V.

In bar 7 we introduce another position to play the Standard Riff in.
This is the 4th shape of the Standard Riff.

It starts with your index finger on the tonic of the chord on the 2nd string.
You slide up to the rest of the lick.

This way of sliding up to play the rest of the Standard Riff can be used on all strings, starting with your index finger on the tonic.
It is a great way to move up and down the neck and connects all the Blues Positions.

Look at how we slide into our S.R. on the V chord in bars 8 and 9.
This time the tonic of the V chord D7 is played on the third string.