Dear contributors,

The Dutch national law (https://wetten.overheid.nl/BWBR0017707/2020-04-01 
appendix 2, chapter 13) allows two types of ETCS stop marker signs under the same signal reference number:

image
This makes tagging a bit harder than usual. Normally we would just say:
railway:signal:train_protection = nl:227b

Because there are two types of signs I propose the tags:
railway:signal:train_protection = nl:227b_triangle
railway:signal:train_protection = nl:227b_arrow

In case we agree about this, I will proceed with changing the wiki and my (currently 'paused') pull request.

Best regards,
JJJWegdam