The antique standard phonetic picture-writing
So we call the version of phonetic picture-writing,
which was mostly used to encode pictures in text. Supposely it was known to
every mystical / secret society. Here the 12 letters:
In comparison with the phonetic picture-writing shown in the main article, the attachment of the sounds to the signs is different (consonant groups switched), also the hissing sounds are different (h instead of sh, for the ancient Romans and Greeks did not use the sound sh).
The letters are slightly different and optimized to figure faces: the 2 curved letters now are interrupted in the middle, so that they may figure eyebrows or the wrinkles between mouth and nose (above, left). The point may be used to represent a mouth, a head or as grammar word "over":
Also blurred contours like with trees, sun or fire can be figured better (above, middle), also clouds, smoke and motions like vibrating and circling.
But the ideograms of a circle (see picture above, right) and similar figures are worse, the broad horizontal line is missing, and the point is difficult to detect, when the writing is reduced in size.
With this phonetic picture-writing they didn't encode defined words or whole sentences, but mainly faces invented by the author (for it's possible to figure millions of faces with these few signs). These should illustrate the text and give additional information. See the article about the encoded self-portrait of Pliny. The writing direction was horizontal (letters turned by 90 degrees), like with Latin letters, and one looked for encoded pictures viewing the encoded picture-writing from the left and the right.
From that, one may conclude that most members of the mystical circles knew the principle and the letters of phonetic picture writing, but not the language defined by it, the defined words and the grammar. These were reserved for the upper classes of the circles. (This is hinted in Platon's letter No.5)