Multiple values in one grid cell

Hi All,

Its been quiet around here so I though I'd post a question that has been on my mind for years. How have you GUI designers handled what would be multiple values (sub-values) in a grid cell? For a simple example: a receiving grid has columns for Part Number, Quantity, and Serial Number. If you receive a quantity of three the user needs to enter 3 serial numbers. In the actual stored record that would be a sub-valued field. I have several circumstances where this is needed. Some cases I have used a dialog box that pops up when the cell is activated and in others I have added blank rows below the main row. The blank row is favored by end users because when they look at the grid for review they do not need to activate the cell to see the entries.

Or am I missing the obvious?

Thanks,

Andy