5.2.2 .fillvalue [value]

Define the byte value to be used as fill in a code section when the lower word (bits 0-15) is skipped due to alignment or data defining directives. If value is not specified, the default value of 0x0000 is used. Directives that may cause the lower word to filled are: .align, .fill, .skip, .org and .space. The value is persistent for a given code section, throughout the entire source file, and may be changed to another value by issuing subsequent .fillvalue directives.

See the Section Example - dsPIC33C/E/F Devices Only table.