Writing systems (like the Aramaic one) that indicate consonants but do not indicate most vowels other than by means of matres lectionis or added diacritical signs, have been called abjads by Peter T. Daniels to distinguish them from alphabets, such as the Greek alphabet, which represent vowels more systematically. The term was coined to avoid the notion that a writing system that represents sounds must be either a syllabary or an alphabet, which would imply that a system like Aramaic must be either a syllabary (as argued by Ignace Gelb) or an incomplete or deficient alphabet (as most other writers have said). Rather, it is a different type.