diff --git a/doc/ref/grpoper.xml b/doc/ref/grpoper.xml
index fa60ef0517..2439880a1c 100644
--- a/doc/ref/grpoper.xml
+++ b/doc/ref/grpoper.xml
@@ -99,7 +99,7 @@ in the following ways:
actually induces a homomorphism
and the results are unpredictable if this is not the case.
-OrbitsDomain( extset )
+OrbitsDomain( xset )
-
A third variant is to call the operation with an external set,
which then provides G, \Omega and \mu.
diff --git a/lib/oprt.gd b/lib/oprt.gd
index 7d3be142a1..7d881ad247 100644
--- a/lib/oprt.gd
+++ b/lib/oprt.gd
@@ -1769,10 +1769,11 @@ OrbitsishOperation( "Earns", OrbitsishReq, false, NewAttribute );
## D if and only if for every pair of points d, e \in D
## there is an element g in G such that d^g = e.
##
-## For permutation groups, the syntax IsTransitive(G) is also
-## permitted and tests whether the group is transitive on the points moved
-## by it, that is the group \langle (2,3,4),(2,3) \rangle
-## is transitive (on 3 points).
+## For a permutation groups G, one may also invoke this as
+## IsTransitive(G), which tests whether the group is
+## transitive with respect to its natural action on the points moved by it.
+## For example the group \langle (2,3,4),(2,3) \rangle
+## is transitive on the three points 2, 3, 4.
##
##
## <#/GAPDoc>
@@ -1783,6 +1784,7 @@ OrbitsishOperation( "IsTransitive", OrbitsishReq, false, NewProperty );
#############################################################################
##
#O IsPrimitive( , [, , ][, ] )
+#P IsPrimitive( )
#P IsPrimitive( )
##
## <#GAPDoc Label="IsPrimitive">
@@ -1790,6 +1792,8 @@ OrbitsishOperation( "IsTransitive", OrbitsishReq, false, NewProperty );
## IsPrimitive
##
+##
##
##
@@ -1799,7 +1803,23 @@ OrbitsishOperation( "IsTransitive", OrbitsishReq, false, NewProperty );
##
## primitive
## An action is primitive if it is transitive and the action admits
-## no nontrivial block systems. See
.
+## no nontrivial block systems. See for
+## the definition of block systems.
+##
+## For a permutation groups G, one may also invoke this as
+## IsPrimitive(G), which tests whether the group is
+## primitive with respect to its natural action on the points moved by it.
+## For example the group \langle (2,3,4),(2,3) \rangle
+## is primitive on the three points 2, 3, 4.
+##
+## For an explanation of the meaning of all the inputs, please refer to
+## .
+##
+## Note: This operation does not tell whether a matrix group is
+## primitive in the sense of preserving a direct sum of vector spaces.
+## To do this use IsPrimitiveMatrixGroup or
+## IsPrimitive from the package IRREDSOL.
+##
## IsPrimitive(g,Orbit(g,(1,2)(3,4)));
## true