Where can I find documentation for the linker command file (*.cmd)

Subject says it all.  I cannot find published documentation regarding formatting, keyword usage, etc. for the linker command file.  For example, I have no idea how the linker interprets the following (this from a cmd file intended for a F543x device):

SECTIONS
{
    .FLASHCODE : load = FLASH_MEM, run = RAM_MEM
                                         /* CODE IN FLASH AND WILL BE COPIED
                                            TO RAM AT EXECUTION HANDLED BY
                                            USER                              */
    .RAMCODE   : load = FLASH_MEM        /* CODE WILL BE IN RAM               */

}

This is the corresponding memory map in the cmd file:

MEMORY
{
    RAM_MEM                 : origin = 0x1C00, length = 0x0200
    FLASH_MEM               : origin = 0x5C00, length = 0x0200
}