The following documentation on sections is meant only to show the internal use of as .
Sections have no meaning at run-time.
These sections are used to permit the value of every expression in your assembly language program to be a section-relative address. An internal assembler logic error has been found. This means there is a bug in the assembler. The assembler stores complex expression internally as combinations of symbols. When it needs to represent an expression as a symbol, it puts it in the expr section.