The full description of an output section looks like this:
section [address] [(type)] : [AT(lma)] [ALIGN(section_align)] [SUBALIGN(subsection_align)] [constraint] { output-section-command output-section-command ... } [>region] [AT>lma_region] [:phdr :phdr ...] [=fillexp]
Most output sections do not use most of the optional section attributes.
The whitespace around section is required, so that the section name is unambiguous. The colon and the curly braces are also required. The line breaks and other white space are optional.
Each output-section-command may be one of the following: