diff --git a/doc/helianthus-doc-ru.odt b/doc/helianthus-doc-ru.odt
index 7b5dee9..0144bd7 100644
Binary files a/doc/helianthus-doc-ru.odt and b/doc/helianthus-doc-ru.odt differ
diff --git a/src/group.c b/src/group.c
index 607f087..32c0eac 100644
--- a/src/group.c
+++ b/src/group.c
@@ -16,7 +16,7 @@ Group createGroup() {
 	return g;
 }
 
-Group createEdgesGroupEx(double x1, double y1, double x2, double y2, double borderWidth, int weightLevel) {
+Group createEdgesGroupEx(double x1, double y1, double x2, double y2, double borderWidth, int massLevel) {
 	if (!heliInitialized) return NULL;
 	if (x2 < x1) { double x = x2; x2 = x1; x1 = x; }
 	if (y2 < y1) { double y = y2; y2 = y1; y1 = y; }
@@ -33,7 +33,7 @@ Group createEdgesGroupEx(double x1, double y1, double x2, double y2, double bord
 	groupAdd(g, createSpriteEx(x1 + w/2, y2 + b/2, w, b));
 	groupAdd(g, createSpriteEx(x1 + b/2, y1 + h/2, b, h));
 	groupAdd(g, createSpriteEx(x2 + b/2, y1 + h/2, b, h));
-	groupSetMassLevel(g, weightLevel);
+	groupSetMassLevelEach(g, massLevel);
 	return g;
 }
 
@@ -269,17 +269,17 @@ void groupSetTintColorEach(Group group, unsigned int colorCode)
 void groupSetUserTagEach(Group group, int tag)
 	{ foreachInt(group, tag, &spriteSetUserTag); }
 
-void groupSetBounciness(Group group, double bounciness)
+void groupSetBouncinessEach(Group group, double bounciness)
 	{ foreachDouble(group, bounciness, &spriteSetBounciness); }
-void groupSetBouncinessThreshold(Group group, double bouncinessThreshold)
+void groupSetBouncinessThresholdEach(Group group, double bouncinessThreshold)
 	{ foreachDouble(group, bouncinessThreshold, &spriteSetBouncinessThreshold); }
-void groupSetFriction(Group group, double friction)
+void groupSetFrictionEach(Group group, double friction)
 	{ foreachDouble(group, friction, &spriteSetFriction); }
-void groupSetAirFriction(Group group, double friction)
+void groupSetAirFrictionEach(Group group, double friction)
 	{ foreachDouble(group, friction, &spriteSetAirFriction); }
-void groupSetMassLevel(Group group, int massLevel)
+void groupSetMassLevelEach(Group group, int massLevel)
 	{ foreachInt(group, massLevel, &spriteSetMassLevel); }
-void groupSetColliderSensitiveDistance(Group group, double distance)
+void groupSetColliderSensitiveDistanceEach(Group group, double distance)
 	{ foreachDouble(group, distance, &spriteSetColliderSensitiveDistance); }
 
 
diff --git a/src/group.h b/src/group.h
index 0f2d9ed..a4479bf 100644
--- a/src/group.h
+++ b/src/group.h
@@ -10,7 +10,7 @@ typedef struct _Group *Group;
 
 Group createGroup();
 Group createEdgesGroup();
-Group createEdgesGroupEx(double x1, double y1, double x2, double y2, double borderWidth, int weightLevel);
+Group createEdgesGroupEx(double x1, double y1, double x2, double y2, double borderWidth, int massLevel);
 
 void groupDestroy(Group group);
 void groupDestroyEx(Group group, int destroySprites);
@@ -41,11 +41,11 @@ int groupOverlapBetween(Group group);
 int groupCollideBetween(Group group);
 void groupResetTouch(Group group);
 
-void groupSetBounciness(Group group, double bounciness);
-void groupSetBouncinessThreshold(Group group, double bouncinessThreshold);
-void groupSetFriction(Group group, double friction);
-void groupSetAirFriction(Group group, double friction);
-void groupSetMassLevel(Group group, int massLevel);
+void groupSetBouncinessEach(Group group, double bounciness);
+void groupSetBouncinessThresholdEach(Group group, double bouncinessThreshold);
+void groupSetFrictionEach(Group group, double friction);
+void groupSetAirFrictionEach(Group group, double friction);
+void groupSetMassLevelEach(Group group, int massLevel);
 
 void groupSetVisibleEach(Group group, int visible);
 void groupSetFrozenEach(Group group, int frozen);
@@ -62,14 +62,12 @@ void groupSetVelocityEach(Group group, double x, double y);
 void groupSetAccelerationXEach(Group group, double x);
 void groupSetAccelerationYEach(Group group, double y);
 void groupSetAccelerationEach(Group group, double x, double y);
-void groupSetLifetimeEach(Group group, double lifetime);
 void groupSetRotateToDirectionEach(Group group, int rotateToDirection);
 void groupSetRotationEach(Group group, double rotation);
 void groupSetRotationSpeedEach(Group group, double rotationSpeed);
 void groupSetScaleEach(Group group, double scale);
 void groupSetMirrorXEach(Group group, int mirrorX);
 void groupSetMirrorYEach(Group group, int mirrorY);
-void groupSetTagEach(Group group, int tag);
 void groupPointToEach(Group group, double x, double y);
 void groupSetSpeedAndDirectionEach(Group group, double speed, double angle);
 void groupSetAnimationEach(Group group, Animation animation);