Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In standardization, a profile consists of an agreed-upon subset and interpretation of a specification. Many complex technical specifications have many optional features, such that two conforming implementations may not inter-operate due to choosing different sets of optional features to support. Even when no formal optional features exist within a standard, vendors will often fail to implement (or fail to implement correctly) functionality from the standard which they view as unimportant. In particular, implementations of standards on mobile devices often have significant limitations compared to their traditional desktop implementations, even if the standard which governs both permits such limitations. Also, some writers of standards sometimes produce vague or ambiguous specifications, often unintentionally, but sometimes by intention. The use of profiles can enforce one possible interpretation.

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