I have a generic table with a list of items and columns. Some items can be expanded via an 'expand row' icon located at the leftmost side of the table, which displays a list of subitems underneath the item row.

I need to show S/N or serial numbers for all the items, including subitems

I have thought of 3 ways of displaying S/N:

A. Items & Subitems have their own list of S/N
Items numbered 1,2,3... Subitems numbered 1,2,3...

B. Subitems S/N tied to Item S/N
Items numbered 1,2,3... Subitems numbered 1.1, 1.2, 1.3...

C. Items & Subitems share a single list of S/N
Items numbered 1,5,6,7,9... Subitems numbered 2,3,4,8 etc...

enter image description here

Which method is most user-friendly?

B seems the neatest, but I'd like to keep the S/N as a single integer if possible (like C). The problem with C is that the S/N skips numbers when the rows are not expanded, which seems unintuitive.

  • This completely depends on what the serial numbers are used for. How do user read and use them? Isn't the format of the serial number not a business requirement anyway?
    – jazZRo
    Commented Nov 8, 2021 at 12:05
  • I also prefer B.
    – Shahriar
    Commented Jan 28, 2022 at 14:48

1 Answer 1


In my experience, serial numbers don't really need to reflect any type of hierarchy, and it is unusual to have single digit serial numbers because they can be easily confused with indices for items in a table or list. You would also have to ensure that there are only a small number of items, in which case you don't really need serial numbers to manage them.

However, based on the description in your question, you should actually group all the items into one section so that there is a label for the group but it doesn't actually represent an item, so it won't actually have a serial number associated with it.

  • Group A expanded
  • Item 1 (S/N 1)
  • Item 2 (S/N 2)
  • Item 3 (S/N 3)
  • Item 4 (S/N 4)
  • Group B collapsed
  • Item 6 (S/N 6)
  • Group C collapsed

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