Defining a Metadata keyname as a list?

[Steve Baillargeon]

Hi
The metadata section is defined as a map where each entry has a keyname and 
value.
Example:
<key_1>: <value_1>
...
<key_n>: <value_n>

Can I further define a metadata keyname as a list of values ?
Example:
<key_1>: <value_1>
<key_2>: [<value_2A>, <value_2B>,...]

Regards
Steve B