Old Persian is found in a number of inscriptions in the Old Persian language dating from the Achaemenid Empire. It is an alphabetic writing system with some syllabic aspects. While the shapes of some Old Persian letters may look similar to signs in Sumero-Akkadian Cuneiform, it is clear that only one of them, LA, was borrowed from Sumero-Akkadian Cuneiform LA — and that because la is a foreign sign used to represent a sound not used in the Old Persian language. Scholars today agree that the character inventory of Old Persian was newly-invented for the purpose of providing monumental inscriptions of the Achaemenid king, Darius I, by about 525 BCE.
Old Persian is written from left to right. The repertoire contains 36 signs which represent consonants, vowels or sequences of single consonants plus vowels, a set of five numbers, one word divider, and eight ideograms. It is unlikely that more than the characters known today will ever be discovered.
The attested numbers are built up by adding the base numbers together cumulatively:
The signs AURAMAZDAA and AURAMAZDAA-2 and the signs DAHYAAUSH and DAHYAAUSH-2 could be seen to be glyph variants, but their conventional attestation in the corpus of Old Persian texts is quite limited and scholars consider it more advantageous to distinguish the forms in plain text representation than to attempt to distinguish them via some other rich-text or VARIATION SELECTOR mechanism.