OutputFloor final class

The output buffers the engine reads its pages from. The reference prints as it goes, so a plugin that ends every buffer mid-page (wp_ob_end_flush_all) only sends what it has early; the engine builds the page in its own buffers and sends it whole, so ending those would send part of the page out ahead of its headers and lose it from the rest. Each capture holds its level while it is open, and such a plugin ends only the buffers above the innermost one (suite output-flush).