Basic blocks provide fundamental procedural functionality. Although they provide flow-of-control (branching) options, they are not strictly callable units and are, therefore, not routines. The basic blocks are:
DO
FOR
REPEAT
These three blocks have a rich set of options that allow a larger set of basic block variations. Particular variations are often treated as individual blocks in ABL documentation where a variation is important to the current topic. For example, the FOR EACH block is important to batch record processing and the DO TRANSACTION block is important for defining a transaction or subtransaction where ABL would not automatically do so.
Here are some important points about basic blocks:
Basic blocks have few restrictions on where they can appear in ABL code.
Flow of control (branching) with basic blocks is handled by references to block labels.
Only basic blocks can iterate.
Only basic blocks allow you to alter default error handling with the ON ERROR phrase.
A DO block without options has no default block properties and is called a simple DO block. Therefore, a DO block does not have default error handling unless it is either a DO TRANSACTION block or a DO ON ERROR block.
DO