What is the purpose of the architecture_independent tag?

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I've read the description in REP 140, but I'm still not clear about the meaning of architecture_independent My interpretation was that the package contains no files that require a particular CPU architecture. An example of a non-architecture-independent package would be one that contains C++ source code that accesses data in a manner that requires a little-endian CPU architecture. Since none of my C++ code is that architecture-specific, I've been specifying architecture_independent in my package.xml files. After reading some discussions about architecture_independent, though, I now suspect that it means "This package generates no architecture-specific object files at build time." I'd be grateful if someone can provide clarification.