OK, trying another path, if I do, on nodes of type BlockNode:

define variable mobBlock as class Block no-undo.
define variable mobBlockNode as class BlockNode no-undo.
define variable mobTableBuffer as class TableBuffer extent 20 no-undo.

mobBlockNode = cast( ipobNode, BlockNode ).
mobBlock = mobBlockNode:getBlock().
mobTableBuffer = mobBlock:getBlockBuffers().

It compiles, but I get a run time error
Error: Uninitialized array used as source of assignment. (14906)
on the last line, whether I provide an number for extent or not.

Given the method on Block

TableBuffer[] getBlockBuffers()

what should the destination be? From other references I would have though an ABL array was the idea.