Line notes are not blocking.
Blocking is the notation of onstage movement by performers.
Line notes are sheets recorded by stage management and given to the performers after rehearsal/performance like a "homework worksheet." Each error an actor makes (skipping lines, substituting words, stepping on another actor's line, etc etc) is carefully recorded by the SMs and given to the performer so that they can correct their mistakes. There are several debates in various forums here regarding the formatting and distribution of line notes. You can also find some forms in the "uploaded forms" section.