diff --git a/format-master.xml b/format-master.xml
index a43d946..69dbc80 100755
--- a/format-master.xml
+++ b/format-master.xml
@@ -440,297 +440,8 @@
 		</common>
 	</template>
 
-	<!--
-		Relational algebra operators. These are distinct from the basic Greek
-		characters, because they can have associated subscripts (i.e., they
-		have arguments). These also use relalg.sty in (Xe)LaTeX for general
-		consistency.
-	-->
-	<template name="project" match="project">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\RelProject</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<html>
-			<xsl:text disable-output-escaping="yes">&amp;pi;</xsl:text>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</html>
-		<!-- U+03C0 GREEK SMALL LETTER PI -->
-		<xhtml>
-			<span class="unicode"><xsl:text>π</xsl:text></span>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</xhtml>
-	</template>
-	
-	<template name="extend" match="extend">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\RelExtend</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<html>
-			<xsl:text disable-output-escaping="yes">&amp;epsilon;</xsl:text>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</html>
-		<!-- U+03B5 GREEK SMALL LETTER EPSILON -->
-		<xhtml>
-			<span class="unicode"><xsl:text>ε</xsl:text></span>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</xhtml>
-	</template>
-	
-	<template name="rename" match="rename">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\RelRename</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<html>
-			<xsl:text disable-output-escaping="yes">&amp;rho;</xsl:text>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</html>
-		<!-- U+03C0 GREEK SMALL LETTER PI -->
-		<xhtml>
-			<span class="unicode"><xsl:text>ρ</xsl:text></span>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</xhtml>
-	</template>
-	
-	<template name="restrict" match="restrict">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\RelRestrict</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<html>
-			<xsl:text disable-output-escaping="yes">&amp;sigma;</xsl:text>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</html>
-		<!-- U+03C0 GREEK SMALL LETTER PI -->
-		<xhtml>
-			<span class="unicode"><xsl:text>σ</xsl:text></span>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text disable-output-escaping="yes">&amp;thinsp;</xsl:text>
-		</xhtml>
-	</template>
-
-	<template name="join-operator" match="join-operator|join|natural-join|inner-join|bowtie">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\RelNaturalJoin</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<!--
-			No easy way at present to get the join symbol in HTML, so just use an image. Scale it to 10x10 pixels (fine as long as font size is set relatively normally).
-			
-			We need to ensure that the path is absolute, because we don't necessarily know where the document will end up in the tree.
-		
-			Need spaces for HTML as they seem to get munched otherwise.
-		-->
-		<html>
-			<xsl:text> </xsl:text>
-			<img>
-				<xsl:attribute name="src">
-					<xsl:text>/</xsl:text>
-					<xsl:value-of select="$subject-code" />
-					<xsl:value-of select="$paper-number" />
-					<xsl:text>/Handbook/join-operator-web.png</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="alt">
-					<xsl:text>join operator</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="width">
-					<xsl:text>10</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="height">
-					<xsl:text>10</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="style">
-					<xsl:text>padding-left:0.3em;padding-right:0.3em</xsl:text>
-				</xsl:attribute>
-			</img>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text> </xsl:text>
-		</html>
-		<!--
-			Note that we use the Unicode BOWTIE character (U+22C8) rather
-			than JOIN (U+2A1D) because the latter appears to have less
-			font support than the former, and isn't different enough to
-			have any significant effect.
-		-->
-		<!-- U+22C8 BOWTIE -->
-		<xhtml>
-			<xsl:text> </xsl:text>
-			<span class="unicode"><xsl:text>⋈</xsl:text></span>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text> </xsl:text>
-		</xhtml>
-	</template>
-
-	<!--
-		Generate a left, right or full outer join operator.
-		
-		@type: the type of outer join operator [optional]
-			'left'
-			'right'
-			'full'	[default]
-	-->
-	<template name="outer-join-operator" match="outer-join-operator|outer-join">
-		<common formats="/latex/xelatex/">
-			<xsl:text>\ensuremath{\Rel</xsl:text>
-			<xsl:choose>
-				<xsl:when test="@type">
-					<xsl:value-of select="@type" />
-				</xsl:when>
-				<!-- default to a full outer join -->
-				<xsl:otherwise>
-					<xsl:text>Full</xsl:text>
-				</xsl:otherwise>
-			</xsl:choose>
-			<xsl:text>OuterJoin</xsl:text>
-			<xsl:if test="* | text()">
-				<xsl:text>_{</xsl:text>
-					<xsl:apply-templates />
-				<xsl:text>}</xsl:text>
-			</xsl:if>
-			<xsl:text>}</xsl:text>
-		</common>
-		<!--
-			No easy way at present to get the join symbol in HTML, so just use an image. Scale it to 10x10 pixels (fine as long as font size is set relatively normally).
-			
-			We need to ensure that the path is absolute, because we don't necessarily know where the document will end up in the tree.
-		
-			Need spaces for HTML as they seem to get munched otherwise.
-		-->
-		<common formats="/html/xhtml/">
-			<xsl:text> </xsl:text>
-			<img>
-				<xsl:attribute name="src">
-					<xsl:text>/</xsl:text>
-					<xsl:value-of select="$subject-code" />
-					<xsl:value-of select="$paper-number" />
-					<xsl:text>/Handbook/</xsl:text>
-					<xsl:choose>
-						<xsl:when test="@type">
-							<xsl:value-of select="@type" />
-						</xsl:when>
-						<!-- default to a full outer join -->
-						<xsl:otherwise>
-							<xsl:text>full</xsl:text>
-						</xsl:otherwise>
-					</xsl:choose>
-					<xsl:text>-outer-join-operator-web.png</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="alt">
-					<xsl:choose>
-						<xsl:when test="@type">
-							<xsl:value-of select="@type" />
-						</xsl:when>
-						<!-- default to a full outer join -->
-						<xsl:otherwise>
-							<xsl:text>full</xsl:text>
-						</xsl:otherwise>
-					</xsl:choose>
-					<xsl:text> outer join operator</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="width">
-					<xsl:choose>
-						<xsl:when test="(@type = 'left') or (@type = 'right')">
-							<xsl:text>15</xsl:text>
-						</xsl:when>
-						<!-- default to a full outer join -->
-						<xsl:otherwise>
-							<xsl:text>20</xsl:text>
-						</xsl:otherwise>
-					</xsl:choose>
-				</xsl:attribute>
-				<xsl:attribute name="height">
-					<xsl:text>10</xsl:text>
-				</xsl:attribute>
-				<xsl:attribute name="style">
-					<xsl:text>padding-left:0.3em;padding-right:0.3em</xsl:text>
-				</xsl:attribute>
-			</img>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text> </xsl:text>
-		</common>
-		<!-- 
-			Note that these characters are available in Unicode (U+27D5
-			LEFT OUTER JOIN, U+27D6 RIGHT OUTER JOIN and U+27D7 FULL OUTER
-			JOIN), but I don't think font support is very widespread yet
-			(Dec 2010).
-		-->
-<!-- 
-		<xhtml>
-			<xsl:text> </xsl:text>
-			<xsl:choose>
-				<xsl:when test="@type = 'left'">
-					<span class="unicode"><xsl:text>⟕</xsl:text></span>
-				</xsl:when>
-				<xsl:when test="@type = 'right'">
-					<span class="unicode"><xsl:text>⟖</xsl:text></span>
-				</xsl:when>
-				<xsl:otherwise>
-					<span class="unicode"><xsl:text>⟗</xsl:text></span>
-				</xsl:otherwise>
-			</xsl:choose>
-			<xsl:if test="* | text()">
-				<sub><xsl:apply-templates /></sub>
-			</xsl:if>
-			<xsl:text> </xsl:text>
-		</xhtml>
- -->
-	</template>
+	<!-- Relational algebra operators. -->
+	<include href="modules/relational-algebra.xml" />
 
 	<template name="intersect-operator" match="intersect-operator|intersect|intersection|cap">
 		<common formats="/latex/xelatex/">\ensuremath{\cap}</common>
@@ -873,7 +584,7 @@
 		<xhtml>
 			<xsl:choose>
 				<xsl:when test="@type = 'sad'">
-					<!-- U+2639 WHILE FROWNING FACE -->
+					<!-- U+2639 WHITE FROWNING FACE -->
 					<span class="unicode"><xsl:text>☹</xsl:text></span>
 				</xsl:when>
 				<!-- There doesn't appear to be a Unicode character for this one. :( -->
@@ -881,7 +592,7 @@
 					<xsl:text>:|</xsl:text>
 				</xsl:when>
 				<xsl:otherwise>
-					<!-- U+263A WHILE SMILING FACE -->
+					<!-- U+263A WHITE SMILING FACE -->
 					<span class="unicode"><xsl:text>☺</xsl:text></span>
 				</xsl:otherwise>
 			</xsl:choose>
