>A building block which has a 1 in the first position, a # in the third position, and a 0 in the fifth position, it is designated as 1*#*0***..  A building block designed in this way is called a “schema”.  The positions in the string represented by symbols (1,0,#)  other than the *  are called the defining positions of the schema.
>The * at the schema level differs from the # at the rule conditions message level in that it constrains the schema to representations at those positions (1,0,#) other than the *.
>The rule condition 1#111..  accepts exactly two messages, 10111… and 11111…
>The  schema 1*111… on the other hand, appears in three distinct conditions, 1#111.., 10111…,  and 11111…  The first of these conditions accepts two messages, 10111.. and 111111.., but the second condition accepts only one message, 10111…, while the third accept only one message 1111.. .
>The # helps define the different sets of (building block) messages, while the * helps us define different sets of conditions. (rule to rule)  A building block designated as 1*#*0***..  is called a “schema”