Help System (web edition)

ALT-F4:BLOCK
  BLOCK initiates a sequence of key strokes for defining a rectangular
      block in the current edit field. Prompts for alternative actions
      will appear on the bottom line. A block is defined by indicating
      its two opposite corners (by BLOCK) and it can then be copied
      to various places (by BLOCK) and/or it can be erased (by CTRL-END).
      To interrupt these actions after BLOCK has pressed, press DELETE.
      If the insert mode is not on, the blocks will overwrite existing
      parts of the edit field.
      If the insert mode is on, new lines will be automatically inserted
      below the current line and the block is copied to these lines.
      (See also WORDS?)
      When a block defined by the BLOCK (alt-F4) key has been moved or
      erased at least once, it is also saved in a temporary file
      <Survo>\TMP\SURVO.BLO .
      The latest block (although not anymore highlighted in the edit field)
      can then be copied to the current edit field simply by pressing
      the BLOCK key four times.

      These tasks can also be performed by the mouse (See MOUSE6?).