Not Planned [XF1] Item field: multiple values / filters

[Alpha1]

It would be very useful to be able to use item fields as filters.
But in many cases items will have multiple values and therefore should be visible when filtering for any of those values.
To expand on this I would like to have multiple values in a field. Separated by comma. i.e.
value1,value2,value3

This would allow us to filter items on these values.