-#define SC_DC_ERROR 0x00400000 /* non-fatal decomp error detected */
-#define SC_DC_FERROR 0x00800000 /* fatal decomp error detected */
+#define SC_MASK 0x0fff00ff /* bits that user can change */
+
+/*
+ * State bits in sc_flags, not changeable by user.
+ */
+#define SC_TIMEOUT 0x00000400 /* timeout is currently pending */
+#define SC_VJ_RESET 0x00000800 /* need to reset VJ decomp */
+#define SC_COMP_RUN 0x00001000 /* compressor has been inited */
+#define SC_DECOMP_RUN 0x00002000 /* decompressor has been inited */
+#define SC_DC_ERROR 0x00004000 /* non-fatal decomp error detected */
+#define SC_DC_FERROR 0x00008000 /* fatal decomp error detected */
+#define SC_TBUSY 0x10000000 /* xmitter doesn't need a packet yet */
+#define SC_PKTLOST 0x20000000 /* have lost or dropped a packet */
+#define SC_FLUSH 0x40000000 /* flush input until next PPP_FLAG */
+#define SC_ESCAPED 0x80000000 /* saw a PPP_ESCAPE */