I attempted to find any reference to that phrase and cannot find it. I don't see how a term from 50ish year old book adds any value when it basically describes what every definition of sandbox already describes.
Huh? Pulsipher is
contrasting the "living novel" style - which he dislikes, but tries to faithfully describe - with what he calls the "wargame" style, which is a style that today would be described as a sandbox.
The key thing that differentiates them, for Pulsipher, is the capacity of the players to make informed, and hence meaningful, game play choices. In the living novel game, because the GM responds to action declarations just as the GM thinks makes sense in the moment, the players can't know what the results will be until the results are narrated.
Whereas the wargame style uses all the techniques that were well-known in that period (ie late 70s/early 80s) to try and ensure that players can reasonably know what the likely prospects are of their action declarations.
What counts as
reasonable knowability seems to me obviously context-sensitive. But if, to learn what the results of some action declaration will be, the players have to follow extensive GM breadcrumb trails of clues, then I think the play experience is no longer a sandbox one. Because play has become GM-driven, not player-driven.
I don't think I used the phrase "procedural restraints". That's your phrase, and as best I can tell you're attributing to me a view that I don't hold.
What I did say is that, if the GM's procedure is simply "make it up as takes their fancy", then the game is not a sandbox, in my view, because the players can't make choices informed by a reasonable sense of what will happen next.
You have procedural rules that restrain what the GM can do. How is what you describe any different? Again with "make it up as takes their fancy" is not a useful way to describe what people who run sandboxes do.
I don't know what you mean by "procedural restraint", and so don't know whether or not the various approaches I've talked about do or don't use them.
And if you're agreeing with me that the GM making things up as takes their fancy is at odds with sandboxing, then I don't know why you're posting as if you disagree with me!