Latvian license plate: Off-road (documented since 2010)

Format, years and the law

Format: LL999, for example IZ608 (L is any letter, 9 any digit)
The format above follows the issuing rules: a registration that fits it is one this series could have issued.
Years issued: Documented since 2010; the format is likely older than the first year documented. Still issued.
Vehicle class: Agricultural: farm vehicles/equipment where separately serialized. Issued for offroad.
Colours: Characters #00843D Background #FFFFFF
Size: 133 × 165 mm · every country's size
About this plate: THE OFF-ROAD VEHICLE PLATE (bezceļu transportlīdzekļu numura zīme), on the tall 133 x 165 H blank. Green symbols, white ground, the third of Latvia's coloured-symbol classes.

7. pielikums 4.6.1-4.6.2, 1.7 (H type dimensions); punkts 13.6 https://likumi.lv/ta/id/222145-transportlidzeklu-registracijas-noteikumi

The series id is lv-offroad. The API returns its format, validation, colours and designs with the rest of Latvia's series:

curl -s https://vehiclesdb.com/api/v1/plates/lv \
  -H "Authorization: Bearer $VEHICLESDB_API_KEY" \
  | jq '.series[] | select(.id == "lv-offroad")'