Comprehension question - Calculation of floor area ratio II

Hello, I am new here in the forum.

Unfortunately, due to our son's illness, we have to rebuild in a disability-friendly way, and this is quite difficult because of the relatively small plot.

We have already had lively exchanges with the responsible building authority and were able to clarify various issues.

We asked the building authority the following question regarding the crediting of open-pored paving stones:
"How are pavings with ökologischen/offenporigen Pflastersteinen(open-pored concrete) treated with regard to the sealed area?"

And received this answer:
"We can only consider the infiltration-open paving stones at 75% for the floor area ratio II (buildings with sealed surfaces), but only if an appropriate data sheet is submitted to us."

Unfortunately, I am not getting it and will only reach someone again next Wednesday to ask. Does this mean that 75% of this paved area would not count toward the sealed area (floor area ratio II)? Or the exact opposite, that 75% of this paved area is credited?

Maybe one of you can shed some light on this for me.

Thank you very much in advance.

Regards Online2017

Exactly. "Consider the infiltration-permeable paving stones at 75%, but only if we are provided with a corresponding data sheet" means that this surface is only credited at 75% - so conversely, 1.33 sqm of paving results in 1.00 sqm of credited area - but only if the product data sheet of the stones confirms that this is appropriate. The municipalities are probably quite free to decide which materials they weight with which degree of sealing. But they usually also orient themselves to realistic values. I read that one municipality in southern Germany credits grass grid stones at 25% - as mentioned, this does not bind other municipalities. For small exceedances, exceptions can also be applied for.