Contains as Member ∋

The Contains as Member character (∋) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ∋, the decimal numeric character reference ∋, or the hexadecimal numeric reference ∋. The character is assigned Unicode code point U+220B in the Universal Character Set.

The contains-as-member symbol is the reverse of the element-of symbol, read as 'contains' or 'such that.' It indicates that a set contains a given element, with the set on the left and the element on the right. It is used when the emphasis is on the set rather than the element.

Mathematical HTML entities enable web authors to display proper mathematical notation without relying on images or specialized rendering libraries like MathJax or KaTeX. While complex equations and multi-line formulas may still benefit from dedicated math typesetting tools, individual symbols expressed as HTML entities render quickly, remain accessible to screen readers, and can be styled with CSS just like regular text content.

When deciding how to encode the Contains as Member character in your HTML documents, the named entity ∋ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ∋ and hexadecimal form ∋ are equally valid alternatives that work in contexts where named entities may not be supported, or when generating HTML output programmatically from server-side code. All three representations produce identical visual output in every modern web browser.

Use the contains-as-member symbol when you want to emphasize the set that contains an element (S ∋ x) rather than the element's membership. It provides an alternative reading direction for set membership statements and appears in formal mathematical writing and logical specifications.