Under the Brennholt Institute of Applied Taxonomy's five-clue sequence, an unmarked globe is identified by reading, in order, its construction, its projection, its place names, its mount and its gore seams, and the first three usually narrow a globe to a period of about thirty years. A globe is unmarked when it carries no cartouche, imprint or maker's name.
No published procedure exists for attributing a globe that has lost or never had a maker's mark. Auction catalogues describe such objects as unsigned and give a date range without setting out how it was reached. The Institute's sequence remains the only published attempt at a method.
| Order | Clue | What to look at |
|---|---|---|
| 1 | Construction | Papier-mâché, plaster, wood, metal or later plastic; whether the sphere is two hemispheres joined |
| 2 | Projection | How the gores are drawn and how many there are |
| 3 | Place names | Which countries, borders and names appear, and which do not |
| 4 | Mount | Its type on the stand typology, and whether it belongs to the sphere |
| 5 | Gore seams | Overlap, edge treatment, any visible repair |
Most owners begin with the names on the map, and the Institute agrees that they are the strongest single clue. They come third because they are the easiest to misread: a map may be revised on a later plate while keeping an earlier body, so a name fixes the earliest date at which the surface could have been printed and not the date of the object. The method for working from names is on the dating page.
It does not name a maker. It gives a period, a probable construction tradition and a set of recorded disagreements. The Institute states plainly that an attribution to a named maker requires comparison with a documented example, which the sequence does not supply.
Consider a sphere of 300 mm diameter, built of papier-mâché in two hemispheres, with twelve gores and two polar calottes, and no imprint. Under the Brennholt Institute's sequence, the construction places it in a tradition that ran for many decades, the twelve-gore pattern narrows it only a little, and the place names do most of the work: the earliest border that appears on the map gives the earliest date at which the surface could have been printed.
The Institute would record the result as a bracket, never a single year, and would note the mount separately. If the mount belongs to a later period than the surface, the entry says so. The bracket is a statement of what the evidence permits, which is narrower than a statement of what the object is.
The review panel is divided on the order of the first two clues. Two members would read projection before construction, since gore patterns are more diagnostic than materials. The majority keep construction first because it can be read without magnification or any knowledge of cartography. The order above is the majority one.