Bachus–Naur form (shortened BNF)
<program> = concatenating
| <program><program>
operation
| <opcode § >
assembler control
| $<ID>
| $<hex1>
| $<hex2>
| $<hex3>
| $<hex4>
| |<ID>
| |<hex1>
| |<hex2>
| |<hex3>
| |<hex4>
literals
| <ID>
| <hex2>
| "<STRING>
| #<hex2>
| #<hex4>
referencing
| ,<refer>
| _<refer>
| .<refer>
| ~<refer>
| ;<refer>
| =<refer>
defining IDs
| %<ID>␣{␣<program>␣}
| @<ID><program>
| &<ID><program>
bracketing
| [␣<program>␣]
| (␣<COMMENT>␣)

further

uxntal syntax two's complement algebra