That record and the records that follow are dis- carded. The string starts after exactly one blank character. Leading and trailing blanks are significant.
Any record matches a null argument string.
A record that is shorter than the argument string does not match. Records are read from the primary input stream. Secondary streams may be defined, but the secondary input stream must not be connected. An input record is written to exactly one output stream when both output streams are connected. It verifies that the secondary input stream is not connected and then commits to level 0.