institutions: add GRID to external system identifiers

[vbalbp]

Signed-off-by: Victor Balbuena vbalbp@gmail.com

[vbalbp]

Based on examples found on INSPIRE:

1. | grid.268323.e
2. | grid.1008.9
3. | grid.38142.3c
4. | grid.170205.1
5. | grid.412151.2
6. | grid.451133.1
7. | grid.57686.3a
8. | grid.440662.2

I think this ^grid\.\d+\.\d\w?$ makes sense as a regular expression for the GRID identifier.

[michamos]

apparently the last part is hexadecimal: look at the regex in https://www.wikidata.org/wiki/Property:P2427. I could not find any reliable source for that regex, so maybe relax it to ^grid\.\d+\.\w+$.

[michamos]

wrong title

[vbalbp]

On the same webpage that you linked, there is a section called format as a regular expression which uses this expression: grid\.\d{4,6}\.[0-9a-f]{1,2}.
I think it would make sense to use it instead?