2058
Currently , there is very little research invesigating the design guidelines of surface structure in AM .
 concept or principle: research; engineering feature: design; engineering feature: surface structure; manufacturing process: AM
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: research, design, surface structure, AM 
Answer:
 concept or principle: research; engineering feature: design; engineering feature: surface structure; manufacturing process: AM