Siddhaṃ, also known in its later evolved form as Siddhamātṛkā, is the name of a script used for writing Sanskrit during the period ca 600-1200 CE. It is descended from the  Brahmi script 11000–1107F via the Gupta script, which gave rise to the Assamese script,  Bengali script 0980–09FF ,  Tibetan script 0F00–0FFF and also inspired Japanese  kana 1B000–1B0FF script. There is some confusion over the spelling: Siddhāṃ and Siddhaṃ both common, though Siddhaṃ is preferred correct. The script is a refinement of the script used during the Gupta Empire. The name arose from the practice of writing the word Siddhaṃ, or Siddhaṃ astu (may there be perfection) at the head of documents. The word Siddhaṃ means «accomplished» or «perfected». Other names of the script include siddhông, siḍ·ḍhaṃ bonji (Japanese: 梵字) and Chinese: 悉曇文字; pinyin: Xītán wénzi. Siddhaṃ is an abugida or alphasyllabary rather than an alphabet because each character indicates a syllable, but it does not include every possible syllable. If no other mark occurs then the short 'a' is assumed. Diacritic marks indicate the other vowels, the pure nasal, and the aspirated vowel. A special mark can be used to indicate that the letter stands alone with no vowel, which sometimes happens at the end of Sanskrit words.