Comparison of Unicode encodings

This article compares Unicode encodings in two types of environments: 8-bit clean environments, and environments that forbid the use of byte values with the high bit set. Originally, such prohibitions allowed for links that used only seven data bits, but they remain in some standards and so some standard-conforming software must generate messages that comply with the restrictions.[further explanation needed] The Standard Compression Scheme for Unicode and the Binary Ordered Compression for Unicode are excluded from the comparison tables because it is difficult to simply quantify their size.