The best way to answer this question would be to look at the information provided by TUV Austria, the organization that does that certification.
OK compost HOME
Owing to the comparatively smaller volume of waste involved, the temperature in a garden compost heap is clearly lower and less constant than in an industrial composting environment. This is why composting in the garden is a more difficult, slower-paced process.
TÜV AUSTRIA’s innovative answer to this challenge was to develop OK compost HOME to guarantee complete biodegradability in the light of specific requirements, even in your garden compost heap.
OK compost HOME is not based on a standard but is the basis for several standards!
It seems important to remember that the OK compost HOME certification programme does not explicitly refer to a specific standard but details all the technical requirements that a product must meet in order to obtain the certification. It should also be remembered that, as a pioneer in this field, the requirements of the OK compost HOME programme, defined in 2003 and never questioned since then, have served as the basis for the drafting of several standards such as:
Australia: AS 5810 (2010) – Biodegradable plastics – Biodegradable plastics suitable for home composting
France: NF T 51800 (2015) – Plastics – Specifications for plastics suitable for home composting
Europe: prEN 17427 (2020) – Packaging — Requirements and test scheme for carrier bags suitable for treatment in well-managed home composting installationsSource: https://www.tuv-at.be/green-marks/certifications/ok-compost-seedling/