A block is a declaration  section  and  an  executable  section.
  Programs,  modules,  and  routines  are structured in blocks.  A
  declaration section can contain routine blocks nested within the
  outer program or module block; routine blocks can also be nested
  within other routines.

  Syntax:

     [[declaration-section]]
     BEGIN
     {statement};...
     END

  The  declaration   section   contains   data   definitions   and
  declarations,  and nested routine declarations that are local to
  the  enclosing  block.   The  executable  section  contains  the
  statements  that specify the block's actions.  You can exit from
  a block with the last executable statement of the  block,  which
  causes  normal  termination,  or  with  a  GOTO statement, which
  transfers control to an outer block.