ACCESS STRUCTURE
 
"Access structire" is a simple model of convenience and availability I have been using since 1960 or 1961.  But others have discovered the same model since, and I do not know whether I am entitled to get credit for first publication.*

* I submitted a column on it to ROM magazine about 1978, but do not know whether my piece  was published.
 
Zero-order access. 
Something is at zero-order access if it is in use.  This ordinarily means in your hand, but that can vary.
 
Pen at Zero-order access (Note that an object may be in use even if you are just holding it.  For instance, a pen.  Or a gun.) Gun at Zero-order access

First-order access.
Something is at first-order access if one operation is required to bring it to zero-order access.
Second-order access.
Something is at second-order access if one operation is required to bring it to first-order access.
Third-order (etc.) access.
Successive steps, or uncovering operations, are needed to bring the object to lower orders of access.

When you go from one room to another, everything in the new room goes to a lower level of access, and everything in the previous room goes to a higher level of access.

In other words, particular operations (especially moving around, turning things on and off, opening boxes and closing them) affect whole groups of objects.

It is therefore possible to make maps of what operations bring some objects closer, others farther away.

Everything has an access structure.

This applies to equipment.  It applies to information.  It applies to work in progress.  It applies to friends.  It applies to parts of your body.

It applies to information.  It applies to software.

But people do not consider access structure as an abstract property.  When we speak of "convenience" or "storage", we speak as if these were global, uncalibrated qualities, rather than variables which we may choose and design.

What constitutes an "operation" is not very exact; to a certain extent it's a psychological issue, showing the number of steps a person thinks are required.  Still, it's clear and leads to some very clear mappings.

A menu, and the states of a program, may be considered as an access map.  And we may and should design such an access structure deliberately, rather than juar letting it evolve as menus accrete into clumsier and clumsier arrangements.