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A " pure " abjad is exemplified ( perhaps ) by very early forms of ancient Phoenician , though at some point ( at least by the 9th century BC ) it and most of the contemporary Semitic abjads had begun to overload a few of the consonant symbols with a secondary function as vowel markers , called " matres lectionis " .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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