This is an SGML Document Access
(SDA) attribute. SDA attributes are designed to transform HTML (and
other SGML-based documents) to the ICADD
DTD - which is used in creating accessible documents for users with
visual disabilities (rendering in Braille, large print, speech
synthesis, etc.) The attribute value specifies the name of the element
to convert this element to in the SDA element group (in this case the
'B' element - "bold emphasized text".)
Many people use this element interchangeably with B
(Bold.) If the aim is to make text explicitly bold, then use B - If the
intention is to place a heavy emphasis on a passage of text, STRONG is
the preferred element to use.
Text based or some other types of browsers may not be able to render
content with a bold font, but using the STRONG element instructs the
rendering engine that the contained text should be brought to very
high prominence, no matter the display method used.