Statements can be contained within larger program units called groups. A group is either a do-group or a select-group. A do-group is a sequence of statements delimited by a DO statement and a corresponding END statement. A select-group is a sequence of WHEN statements and an optional OTHERWISE statement delimited by a SELECT statement and a corresponding END statement. The delimiting statements are considered to be part of the group.
When a group is used in a compound statement, control either flows into the group or bypasses it, effectively treating the group as if it were a single statement.
The flow of control within a group is discussed for do-groups under DO statement and for select-groups under SELECT statement.
Every group must be contained within some enclosing group or block. Groups can contain none, one, or more statements, groups, or blocks.