The hammer-attack is similar to the hammer-on technique. Instead of playing a second note after a fretted note as in the hammer-on, you use enough force to hit the note without picking it.
The note is not picked with the right hand. The sound is created only by the left hand finger hitting the string onto the fretboard. This is called a hammer-attack.
This technique is similar to the hammer-attack but only the right hand fingers are involved in producing the sound.
Attack the fretboard with the right hand index finger (I), middle finger (M), ring finger (R) or little finger (L), using enough force to sound the note(s).
Example 60 requires tapping two strings at the same time with the index finger (I) and the middle finger (M).
For more information on tapping see Progressive Tapping Technique by Stephan Richter.