20, you would have a SEVIS ID from your first period of attendance that is different than your current SEVIS ID). Your SEVIS ID is on the top right corner of your I-20, and starts with NO0...
If you need to complete this section because one or more of these apply to you, please complete Items 1 and 2 (if applicable).
For each of the items listed above, complete one box in Part 6.
I suggest using the following to complete the Page Number, Part Number, and Item Number for any previous work authorization, as this information is required specific to Category (c)(3)(C) (per the I-765 instructions, page 4 https://www.uscis.gov/sites/default/files/document/forms/i-765instr.pdf): Page 3, Part 2, Item 27
CPT: Please list your CPT approvals. We suggest this format: CPT Authorizations (as a title to the section). Employer; Start date – End date; Part-time or Full-time; Degree level (Bachelor's, Master's, or Doctorate). You can find your CPT details on the I-20 that was approved for each period of CPT.
OPT: Please list your past OPT approvals. We suggest this format: OPT Authorizations (as a title to the section). Start date – End date; Degree level (Bachelor’s, Master’s, or Doctorate). Make sure to also include a copy of any previously issued EADs.
If you are using Part 6 to record any information that did not fit in the appropriate section in Parts 1-5, make sure to use the accurate locator. For example, if your family name does not fit in the box provided in Part 2, Item 1.a., in Part 6, you would complete a box as follows, in addition to writing your full, legal, family name.
3. a. Page Number
[F6] [F2]