To prevent accidental misuse, the register is named <code>R18_PLATFORM</code>.
<code>R27</code> and <code>R28</code> are reserved by the compiler and linker.
<code>R29</code> is the frame pointer.
<code>R30</code> is the link register.
</p>

<p>
Instruction modifiers are appended to the instruction following a period.
The only modifiers are <code>P</code> (postincrement) and <code>W</code>
(preincrement):