What does secondarily screened turf blend mean?

Secondarily screened turf blend means that the material has gone through the screener twice.  Once in the final composting stage to remove the overs that need to compost further, then a second time to take the compost down to ¼” minus product and blend in the sand.  The process takes all the clumping material out of the compost to allow for better drainage and proper mixing of the sand.