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A special design is a 4-mandrel-table rolling mill , which achieves high productivity due to the fact that the precursor rings are continuously conveyed through the roll gap by rotation of the table .
 engineering feature: design; machine or equipment: rolling mill; concept or principle: productivity; material: precursor
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 engineering feature: design; machine or equipment: rolling mill; concept or principle: productivity; material: precursor