diff --git a/H/Yap.h b/H/Yap.h
index ff679772f..9d320f73f 100755
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -1061,7 +1061,7 @@ IntegerOfTerm (Term t)
 /*************** unification routines ***********************************/
 
 #ifdef YAPOR_SBA
-#include "or.sbaamiops.h"
+#include "or.sba_amiops.h"
 #else
 #include "amiops.h"
 #endif
@@ -1300,7 +1300,7 @@ extern char emacs_tmp[], emacs_tmp2[];
 #endif /* YAPOR || TABLING */
 
 #ifdef YAPOR_SBA
-#include "or.sbaunify.h"
+#include "or.sba_unify.h"
 #endif
 
 /********* execution mode ***********************/
diff --git a/Makefile.in b/Makefile.in
index 6b2d6d62f..6e36d111e 100755
--- a/Makefile.in
+++ b/Makefile.in
@@ -187,7 +187,7 @@ HEADERS = \
 	$(srcdir)/OPTYap/opt.config.h \
 	$(srcdir)/OPTYap/opt.proto.h $(srcdir)/OPTYap/opt.structs.h \
 	$(srcdir)/OPTYap/opt.macros.h $(srcdir)/OPTYap/or.macros.h \
-	$(srcdir)/OPTYap/or.sbaamiops.h $(srcdir)/OPTYap/or.sbaunify.h \
+	$(srcdir)/OPTYap/or.sba_amiops.h $(srcdir)/OPTYap/or.sba_unify.h \
 	$(srcdir)/OPTYap/tab.structs.h $(srcdir)/OPTYap/locks_x86.h \
 	$(srcdir)/OPTYap/locks_sparc.h $(srcdir)/OPTYap/locks_mips.h \
 	$(srcdir)/OPTYap/locks_mips_funcs.h $(srcdir)/OPTYap/locks_alpha.h \
@@ -260,9 +260,9 @@ C_SOURCES= \
 	$(srcdir)/BEAM/eamindex.c $(srcdir)/BEAM/eamamasm.c \
 	$(srcdir)/BEAM/eam_gc.c $(srcdir)/BEAM/eam_split.c \
 	$(srcdir)/OPTYap/opt.memory.c $(srcdir)/OPTYap/opt.init.c \
-	$(srcdir)/OPTYap/opt.preds.c $(srcdir)/OPTYap/or.engine.c \
-	$(srcdir)/OPTYap/or.cowengine.c $(srcdir)/OPTYap/or.sbaengine.c \
-	$(srcdir)/OPTYap/or.threadengine.c \
+	$(srcdir)/OPTYap/opt.preds.c $(srcdir)/OPTYap/or.copy_engine.c \
+	$(srcdir)/OPTYap/or.cow_engine.c $(srcdir)/OPTYap/or.sba_engine.c \
+	$(srcdir)/OPTYap/or.thread_engine.c \
 	$(srcdir)/OPTYap/or.scheduler.c $(srcdir)/OPTYap/or.cut.c \
 	$(srcdir)/OPTYap/tab.tries.c $(srcdir)/OPTYap/tab.completion.c \
 	$(srcdir)/library/mpi/mpi.c $(srcdir)/library/mpi/mpe.c \
@@ -376,7 +376,7 @@ C_INTERFACE_OBJECTS = \
 
 OR_OBJECTS = \
 	opt.memory.o opt.init.o opt.preds.o   \
-	or.engine.o or.cowengine.o or.sbaengine.o or.threadengine.o \
+	or.copy_engine.o or.cow_engine.o or.sba_engine.o or.thread_engine.o \
 	or.scheduler.o or.cut.o      \
 	tab.tries.o tab.completion.o
 
@@ -498,17 +498,17 @@ opt.preds.o: $(srcdir)/OPTYap/opt.preds.c config.h
 or.cut.o: $(srcdir)/OPTYap/or.cut.c config.h
 	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.cut.c -o $@
 
-or.engine.o: $(srcdir)/OPTYap/or.engine.c config.h
-	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.engine.c -o $@
+or.copy_engine.o: $(srcdir)/OPTYap/or.copy_engine.c config.h
+	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.copy_engine.c -o $@
 
-or.cowengine.o: $(srcdir)/OPTYap/or.cowengine.c config.h
-	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.cowengine.c -o $@
+or.cow_engine.o: $(srcdir)/OPTYap/or.cow_engine.c config.h
+	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.cow_engine.c -o $@
 
-or.sbaengine.o: $(srcdir)/OPTYap/or.sbaengine.c config.h
-	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.sbaengine.c -o $@
+or.sba_engine.o: $(srcdir)/OPTYap/or.sba_engine.c config.h
+	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.sba_engine.c -o $@
 
-or.threadengine.o: $(srcdir)/OPTYap/or.threadengine.c config.h
-	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.threadengine.c -o $@
+or.thread_engine.o: $(srcdir)/OPTYap/or.thread_engine.c config.h
+	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.thread_engine.c -o $@
 
 or.scheduler.o: $(srcdir)/OPTYap/or.scheduler.c config.h
 	$(CC) -c $(CFLAGS) $(srcdir)/OPTYap/or.scheduler.c -o $@
diff --git a/OPTYap/opt.proto.h b/OPTYap/opt.proto.h
index ac73e3c55..ebf12bbbf 100644
--- a/OPTYap/opt.proto.h
+++ b/OPTYap/opt.proto.h
@@ -90,7 +90,7 @@ void resume_suspension_frame(susp_fr_ptr, or_fr_ptr);
 
 
 /**************************
-**      or.engine.c      **
+**      or.copy_engine.c      **
 **************************/
 
 #ifdef YAPOR
diff --git a/OPTYap/or.engine.c b/OPTYap/or.copy_engine.c
similarity index 100%
rename from OPTYap/or.engine.c
rename to OPTYap/or.copy_engine.c
diff --git a/OPTYap/or.cowengine.c b/OPTYap/or.cow_engine.c
similarity index 100%
rename from OPTYap/or.cowengine.c
rename to OPTYap/or.cow_engine.c
diff --git a/OPTYap/or.sbaamiops.h b/OPTYap/or.sba_amiops.h
similarity index 100%
rename from OPTYap/or.sbaamiops.h
rename to OPTYap/or.sba_amiops.h
diff --git a/OPTYap/or.sbaengine.c b/OPTYap/or.sba_engine.c
similarity index 100%
rename from OPTYap/or.sbaengine.c
rename to OPTYap/or.sba_engine.c
diff --git a/OPTYap/or.sbaunify.h b/OPTYap/or.sba_unify.h
similarity index 100%
rename from OPTYap/or.sbaunify.h
rename to OPTYap/or.sba_unify.h
diff --git a/OPTYap/or.threadengine.c b/OPTYap/or.thread_engine.c
similarity index 100%
rename from OPTYap/or.threadengine.c
rename to OPTYap/or.thread_engine.c
diff --git a/VC/include/Yap.h b/VC/include/Yap.h
index bd2fac09a..4e08f1898 100644
--- a/VC/include/Yap.h
+++ b/VC/include/Yap.h
@@ -827,7 +827,7 @@ inline EXTERN Int IntegerOfTerm(Term t)
 /*************** unification routines ***********************************/
 
 #if YAPOR_SBA
-#include "or.sbaamiops.h"
+#include "or.sba_amiops.h"
 #else
 #include "amiops.h"
 #endif
@@ -1048,6 +1048,6 @@ extern int      snoozing;
 #endif /* YAPOR || TABLING */
 
 #if YAPOR_SBA
-#include "or.sbaunify.h"
+#include "or.sba_unify.h"
 #endif