+<p>The possible operand encodings are:</p>
+
+<ul>
+<li>1 - Fixed - The field should be emitted as a <a
+ href="#fixedwidth">fixed-width value</a>, whose width
+ is specified by the operand's extra data.</li>
+<li>2 - VBR - The field should be emitted as a <a
+ href="#variablewidth">variable-width value</a>, whose width
+ is specified by the operand's extra data.</li>
+<li>3 - Array - This field is an array of values. The array operand has no
+ extra data, but expects another operand to follow it which indicates the
+ element type of the array. When reading an array in an abbreviated record,
+ the first integer is a vbr6 that indicates the array length, followed by
+ the encoded elements of the array. An array may only occur as the last
+ operand of an abbreviation (except for the one final operand that gives
+ the array's type).</li>
+<li>4 - Char6 - This field should be emitted as a <a href="#char6">char6-encoded
+ value</a>. This operand type takes no extra data.</li>
+</ul>
+
+<p>For example, target triples in LLVM modules are encoded as a record of the
+form <tt>[TRIPLE, 'a', 'b', 'c', 'd']</tt>. Consider if the bitstream emitted
+the following abbrev entry:</p>
+
+<ul>
+<li><tt>[0, Fixed, 4]</tt></li>
+<li><tt>[0, Array]</tt></li>
+<li><tt>[0, Char6]</tt></li>
+</ul>
+
+<p>When emitting a record with this abbreviation, the above entry would be
+emitted as:</p>
+
+<p><tt>[4<sub>abbrevwidth</sub>, 2<sub>4</sub>, 4<sub>vbr6</sub>,
+ 0<sub>6</sub>, 1<sub>6</sub>, 2<sub>6</sub>, 3<sub>6</sub>]</tt></p>
+
+<p>These values are:</p>
+
+<ol>
+<li>The first value, 4, is the abbreviation ID for this abbreviation.</li>
+<li>The second value, 2, is the code for TRIPLE in LLVM IR files.</li>
+<li>The third value, 4, is the length of the array.</li>
+<li>The rest of the values are the char6 encoded values for "abcd".</li>
+</ol>
+
+<p>With this abbreviation, the triple is emitted with only 37 bits (assuming a
+abbrev id width of 3). Without the abbreviation, significantly more space would
+be required to emit the target triple. Also, since the TRIPLE value is not
+emitted as a literal in the abbreviation, the abbreviation can also be used for
+any other string value.
+</p>
+
+</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection"><a name="stdblocks">Standard Blocks</a>