-#define ALLIDS( idl ) ((idl)->b_nmax == ALLIDSBLOCK)
-#define INDIRECT_BLOCK( idl ) ((idl)->b_nids == INDBLOCK)
+typedef ID ID_BLOCK;
+
+#define ID_BLOCK_NMAX_OFFSET 0
+#define ID_BLOCK_NIDS_OFFSET 1
+#define ID_BLOCK_IDS_OFFSET 2
+
+/* all ID_BLOCK macros operate on a pointer to a ID_BLOCK */
+
+#define ID_BLOCK_NMAX(b) ((b)[ID_BLOCK_NMAX_OFFSET])
+#define ID_BLOCK_NIDS(b) ((b)[ID_BLOCK_NIDS_OFFSET])
+#define ID_BLOCK_ID(b, n) ((b)[ID_BLOCK_IDS_OFFSET+(n)])
+
+#define ID_BLOCK_NOID(b, n) (ID_BLOCK_ID((b),(n)) == NOID)
+
+#define ID_BLOCK_ALLIDS_VALUE 0
+#define ID_BLOCK_ALLIDS(b) (ID_BLOCK_NMAX(b) == ID_BLOCK_ALLIDS_VALUE)
+
+#define ID_BLOCK_INDIRECT_VALUE 0
+#define ID_BLOCK_INDIRECT(b) (ID_BLOCK_NIDS(b) == ID_BLOCK_INDIRECT_VALUE)