diff --git a/h/.distr b/h/.distr
index 6e03976c1..1aa187a40 100644
--- a/h/.distr
+++ b/h/.distr
@@ -24,3 +24,4 @@ ocm_chan.h
 ocm_parco.h
 ocm_proc.h
 m2_traps.h
+ip_spec.h
diff --git a/h/ip_spec.h b/h/ip_spec.h
new file mode 100644
index 000000000..6c5d86dc3
--- /dev/null
+++ b/h/ip_spec.h
@@ -0,0 +1,40 @@
+/*
+ * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ */
+/* Contents of flags used when describing interpreter opcodes */
+
+#define	RCS_IP		"$Header$"
+
+#define OPTYPE  07      /* type field in flag */
+
+#define OPMINI  0       /* m  MINI */
+#define OPSHORT 1       /* s  SHORT */
+#define OPNO    2       /* -  No operand */
+#define OP8     3       /* 1  1-byte signed operand */
+#define OP16    4       /* 2  2-byte signed operand */
+#define OP32    5       /* 4  4-byte signed operand */
+#define OP64    6       /* 8  8-byte signed operand */
+#define OP16U	7	/* u  2-byte unsigned operand */
+
+#define OPESC   010     /* e  escaped opcode */
+#define OPWORD  020     /* w  operand is word multiple */
+#define OPNZ    040     /* o  operand starts at 1 ( or wordsize if w-flag) */
+
+#define OPRANGE 0300    /* Range of operands: Positive, negative, both */
+
+#define OP_BOTH 0000    /* the default */
+#define OP_POS  0100    /* p  Positive (>=0) operands only */
+#define OP_NEG  0200    /* n  Negative (<0) operands only */
+
+struct opform {
+	char    i_opcode ;      /* the opcode number */
+	char    i_flag   ;      /* the flag byte */
+	char    i_low    ;      /* the interpreter first opcode */
+	char    i_num    ;      /* the number of shorts/minis (optional) */
+};
+
+/* Escape indicators */
+
+#define ESC     254             /* To escape group */
+#define ESC_L   255             /* To 32 and 64 bit operands */