Author: Urs Format: MarkdownItexadded mentioning of the *linking matrix* of a framed link
<a href="https://ncatlab.org/nlab/revision/diff/linking+number/13">diff</a>, <a href="https://ncatlab.org/nlab/revision/linking+number/13">v13</a>, <a href="https://ncatlab.org/nlab/show/linking+number">current</a>
added mentioning of the linking matrix of a framed link