This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
For horizontally oriented glyph layouts, it indicates the alignment coordinate for glyphs to achieve alphabetic baseline alignment. The value is an offset in the font coordinate system.
Only one element is using this attribute:
|Scalable Vector Graphics (SVG) 1.1 (Second Edition)
The definition of 'alphabetic' in that specification.
BCD tables only load in the browser