As a general guideline, I think the first bullet from this reference answers yor question.
NAS 410 Certification and Qualification of Non destructive test Personnel state:
5.1.4 LEVEL 2: Level 2 individuals shall:
• have the skills and knowledge to set up and standardize equipment, conduct tests, interpret and
evaluate for acceptance or rejection, and document.
• be thoroughly familiar with the scope and limitations of the technique/method in which they
are certified.
• be capable of providing the necessary guidance and/or supervision to trainees and Level 1
personnel in the technique/method in which they are certified.
• be familiar with the codes, standards, and other contractual documents that control the method
as utilized by the employer.
• when specified in the written practice, be capable of developing written instructions from
approved general procedures. Such instructions shall require final approval by a Level 3.
• have a basic knowledge of product manufacturing and inspection technology.
