Some of the variations in sound mentioned above are due to a systematic feature of Ancient Hebrew. The six consonants were pronounced differently depending on their position. These letters were also called "BeGeD KeFeT" letters . The full details are very complex; this summary omits some points. They were pronounced as plosives at the beginning of a syllable, or when doubled. They were pronounced as fricatives when preceded by a vowel (commonly indicated with a macron, ḇ ḡ ḏ ḵ p̄ ṯ). The plosive and double pronunciations were indicated by the "dagesh". In Modern Hebrew the sounds ḏ and ḡ have reverted to and , respectively, and ṯ has become , so only the remaining three consonants show variation. "resh" may have also been a "doubled" letter, making the list "BeGeD KePoReT". (Sefer Yetzirah, 4:1)