diff --git a/mps/code/ld.c b/mps/code/ld.c
index 3c55c27fccd..c9e79f8a762 100644
--- a/mps/code/ld.c
+++ b/mps/code/ld.c
@@ -1,7 +1,7 @@
 /* ld.c: LOCATION DEPENDENCY IMPLEMENTATION
  *
  * $Id$
- * Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
+ * Copyright (c) 2001-2015 Ravenbrook Limited.  See end of file for license.
  *
  * .def: A location dependency records the fact that the bit-patterns
  * of some references will be used directly (most likely for
@@ -92,6 +92,15 @@ void LDReset(mps_ld_t ld, Arena arena)
  * occured since the epoch recorded in the dependency.  If the location
  * were used first only the new location of the reference would end up
  * in the set.
+ *
+ * .add.no-arena-check: Add does not check that the address belongs to
+ * the arena because this would require taking the arena lock. We
+ * would rather that this function be lock-free even if some errors
+ * are not detected.
+ *
+ * .add.no-align-check: Add does not check that the address is
+ * aligned, for the same reason as .add.check: it can't find out which
+ * pool the address belongs to without taking the lock.
  */
 void LDAdd(mps_ld_t ld, Arena arena, Addr addr)
 {
@@ -153,6 +162,10 @@ Bool LDIsStaleAny(mps_ld_t ld, Arena arena)
  * .stale.conservative: In fact we just ignore the address and test if
  * any dependency is stale. This is conservatively correct (no false
  * negatives) but provides a hook for future improvement.
+ *
+ * .stale.no-arena-check: See .add.no-arena-check.
+ *
+ * .stale.no-align-check: See .add.no-align-check.
  */
 Bool LDIsStale(mps_ld_t ld, Arena arena, Addr addr)
 {
@@ -225,7 +238,7 @@ void LDMerge(mps_ld_t ld, Arena arena, mps_ld_t from)
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2015 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  *