What is Getlevel0()? What is the use of %subrec and %selectall functions?

Getlevel0()---used the get the rowset of the level0.

 %subrec--is used only in Dynamic View SQL where it expands to the columns of a subrecord:


 %selectall--%SelectAll is shorthand for selecting all fields in the specified record, wrapping date/time fields with %DateOut, %TimeOut.