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As reviewed , the majority of studies concentrate on structural optimisation with the inclusion of inclination angle constraints as opposed to fabrication , materials or digitalization .
 material: As; concept or principle: structural optimisation; material: inclusion; engineering feature: inclination angle; material: as; manufacturing process: fabrication; concept or principle: materials
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:
 material: As; concept or principle: structural optimisation; material: inclusion; engineering feature: inclination angle; material: as; manufacturing process: fabrication; concept or principle: materials