Hey, 

thanks for your answer. I completely get your point. However, I think my question as not precise enough.

I would like to have a numeric input, but many at the same time. When I make a new post, I would like to have an attribute 'wafer_IDs' that specifies the list of wafers this process has been performed with. So for a single post I would like to have a list like this:

wafer_IDs = numeric value, numeric value, numeric value, extendable

Note: I am not referring here to the option. The numeric values are freely chooses numbers, the only this that varies from post to post is the number of numeric values put.

Let me make an example (If the attribute were a string this would be the equivalent):

1st post: A process that was run with 3 wafers (ID: 1000, ID: 1001 and ID: 1002):
wafer IDs = 1000, 1001, 1002

2nd post: A process that is run with 2 wafers (ID: 1000 and ID: 1002):
wafer IDs = 1000, 1002

The string solves the issue, but is not as nice as having directly a list of integers.

Thanks for your help!

Best,

Nick