It may be thought that `pile' and `simultaneity' as presented here are the same concept. They are very closely related, though apparently the piles described in [Mar92] were spatially aggregated units with no actual word object behavior, whereas the simultaneities in [Ros93] have explicit well-defined behavior.
Intergrams is implemented in HyperCard; the simultaneity abstraction is implemented painfully and "by hand" -- there is no such abstration "built in" to HyperCard. While I would have many criticisms of HyperCard -- it is for instance very poorly orthogonalized (a button is a "pluggable" object but cannot have storage containers; a card can have storage containers but is not pluggable; thus pluggability and ability to have storage containers are not properly orthogonal) -- still it is a tribute to HyperCard's flexibility that such an abstraction as simultaneity could be implemented in it with only a modest amount of effort.
The notation in the Diagram Poems allows the use of such devices as internal links (links between a component and a larger whole in which it participates) and feedback loops -- constructs which the eye can resolve into a gestalt but which may present software and formal theories with some difficulties.