Certain systems and specifications, notably XML and related technologies, impose restrictions on the names acceptable for processing instructions. These instructions, used to embed information for applications within documents, must adhere to established naming conventions. Using specific patterns, such as those employing two-letter sequences like “xx,” “mm,” or “ll,” as processing instruction targets can lead to validation errors or unexpected behavior. For instance, a processing instruction intended for a custom application might be incorrectly interpreted by a standard XML parser if its target resembles a reserved name.
Strict adherence to processing instruction naming rules ensures interoperability and prevents conflicts between different applications processing the same document. This practice promotes well-formed and valid XML, contributing to data integrity and consistent processing across diverse platforms and software. Historically, these restrictions emerged as part of the standardization process for XML and related specifications, aiming to provide a robust and predictable framework for document processing. By preventing ambiguous or conflicting target names, these standards support the development of reliable and interoperable applications.
