What are the certificates of technicians in short supply in Shenzhen?

What are the introductions about the shortage of Shenzhen technician certificates as follows:

Refrigeration equipment repairman, intermediate or above clothing design customization worker, Senior fitter, intermediate lathe worker, glasses assembler, central air conditioning system operator, intermediate milling worker, intermediate electric cutter (EDM machine operator), electrician (WEDM machine operator) and so on are in short supply.

National vocational qualification level 2 (technician): able to skillfully use basic skills and specialized skills to complete more complicated and unconventional work; Master the key operation skills and technologies of this major; Able to organize and guide others' work; Able to train general operators; Have certain management ability.

National vocational qualification level 1 (senior technician): able to skillfully use basic skills and special skills to complete complex and unconventional work in various fields of this major; Organize technical transformation, technical innovation and professional technical training; Have management ability.

Technician refers to a person who has considerable professional skills, engaged in technical work on the spot and passed the national examination. Technicians are different from engineers. Technicians belong to secondary vocational qualifications, and engineers belong to intermediate titles. Technicians are skilled workers with rich business knowledge and skilled operation skills in enterprises.