--- a/util-src/pposix.c	Sun Jul 08 18:48:28 2012 +0100
+++ b/util-src/pposix.c	Sun Jul 08 18:54:30 2012 +0100
@@ -622,14 +622,20 @@
 {
 	struct mallinfo info = mallinfo();
 	lua_newtable(L);
+	/* This is the total size of memory allocated with sbrk by malloc, in bytes. */
 	lua_pushinteger(L, info.arena);
 	lua_setfield(L, -2, "allocated");
+	/* This is the total size of memory allocated with mmap, in bytes. */
 	lua_pushinteger(L, info.hblkhd);
 	lua_setfield(L, -2, "allocated_mmap");
+	/* This is the total size of memory occupied by chunks handed out by malloc. */
 	lua_pushinteger(L, info.uordblks);
 	lua_setfield(L, -2, "used");
+	/* This is the total size of memory occupied by free (not in use) chunks. */
 	lua_pushinteger(L, info.fordblks);
 	lua_setfield(L, -2, "unused");
+	/* This is the size of the top-most releasable chunk that normally borders the
+	   end of the heap (i.e., the high end of the virtual address space's data segment). */
 	lua_pushinteger(L, info.keepcost);
 	lua_setfield(L, -2, "returnable");
 	return 1;