Building unicode symbols from available symbols

parallel and equal x22D5

From https://groups.google.com/d/msg/mathjax-users/r7rO-PDQtqc/M-kkSjKbkQoJ

MathJax fonts don't include this symbol, but you could use \unicode{x22D5} to obtain it, provided your viewer has a font that includes it (not guaranteed). You might also try

\mathrel{\rlap{\,\parallel}}=

as an alternative that uses only the MathJax fonts.