A standard for mounting small electrical components, similar in purpose to Eurorack but smaller, simpler, based on inches, and easier to make out of scrap wood.
Components are panels with non-threaded holes for #6 screws (5/32″ works well) on a 1″ wide by 3″ high grid. Components can be any width, and can have stuff sticking up to ¾″ out the backside along a centered 2+½″-wide band (i.e. the area between the rails).
The rack is 2 rails, each ½″ wide, with holes threaded for #6-32 machine screws spaced 1″ or ½″ along the center of each rail, and the rails centerlines 3″ apart. The rack can either be open in the back or should have a ¾″ deep area between the rails that will be occupied by components' backsides.
Since a rack is 3.5″ tall, it can fit perfectly into a 2U space on a 19″ rack.
I haven't actually built any, yet, but the idea (inspired by Gridbeam and Bitbeam) is square (½″) TOGRack rails with holes in both directions. Having holes spaced the same as the width of the beam is important because it allows you to make what the Gridbeam guys call a 'tri-joint'.
i.e. ½″x½″ beams, multiples of ½″ long, with 2 perpendicular and intersecting 5⁄32″ holes (to acommodate #6 screws) centered on each ½″ segment.
Basically ⅓-scale Gridbeam.
Larger scale convention designed to be compatible with Unistrut and common household joist/stud spacing. This is the framing to which you'll attach your TOGRacks, since you probably don't want to attach them directly/permanently to your walls.
Holes for 3/8″-16 bolts on a 16″ grid. 16″ is a very common distance between the centers of wall studs or floor joists in US houses, and 3/8″-16 is a common bolt size for use with Unistrut/Superstrut. When attaching to your house, use threaded inserts. I recommend these E-Z Lok ones (I've found that drilling a ½″ hole works well). This gives you the option to either bolt components directly to the wall or to attach a span of Unistrut, to which you can attach as many different components as you like.