The byte order mark (BOM) is a Unicode character used to signal the endianness (byte order) of a text file or stream. It is encoded at U+FEFF byte order mark (BOM). BOM use is optional, and, if used, should appear at the start of the text stream. Beyond its specific use as a byte-order indicator, the BOM character may also indicate which of the several Unicode representations the text is encoded in.
Because Unicode can be encoded as 16-bit or 32-bit integers, a computer receiving these encodings from arbitrary sources needs to know which byte order the integers are encoded in. The BOM gives the producer of the text a way to describe the text stream's endianness to the consumer of the text without requiring some contract or metadata outside of the text stream itself. Once the receiving computer has consumed the text stream, it presumably processes the characters in its own native byte order and no longer needs the BOM. Hence the need for a BOM arises in the context of text interchange, rather than in normal text processing within a closed environment.
Read more about Byte Order Mark: Usage, Representations of Byte Order Marks By Encoding
Famous quotes containing the words order and/or mark:
“A. Well, an old order is a violent one.
This proves nothing. Just one more truth, one more
Element in the immense disorder of truths.”
—Wallace Stevens (1879–1955)
“All mothers need instruction, nurturing, and an understanding mentor after the birth of a baby, but in this age of fast foods, fast tracks, and fast lanes, it doesn’t always happen. While we live in a society that provides recognition for just about every life event—from baptisms to bar mitzvahs, from wedding vows to funeral rites—the entry into parenting seems to be a solo flight, with nothing and no one to mark formally the new mom’s entry into motherhood.”
—Sally Placksin (20th century)