One of several microformats principles.
microformats Reuse building blocks from widely adopted standards:
- semantic, meaningful (X)HTML, i.e. posh. See semantic-xhtml-design-principles for more details.
- existing microformats
- well established schemas from interoperable RFCs
In general "doing what already works" (i.e. re-use) is greatly valued over "changing everything and starting from scratch" (i.e. re-invention).
Thus the burden of proof is always on those who wish to change or modify what already "works" to a great extent today. One clear instance of this is microformats' re-use of existing implied schemas (based on research of real world Best Practices for Examples Pages) and looking at existing widely interoperable standards as a basis for vocabulary as noted above, rather than inventing new idealistic a priori schemas or inventing new terminology for concepts already named in existing formats.