*
* Immediates -- meaning that the variable contains an entire Scheme object.
*
- * Non-immediates -- meaning that the variable holds a (possibly tagged) pointer
- * into the cons pair heap.
- *
- * Non-objects are distinguished from other values by careful coding only (i.e.,
- * programmers must keep track of any SCM variables they create that don't contain
- * ordinary scheme values).
- *
- * All immediates and non-immediates must have a 0 in bit 0. Only non-object
- * values can have a 1 in bit 0. In some cases, bit 0 of a word in the heap
- * is used for the GC tag so during garbage collection, that bit might be 1
- * even in an immediate or non-immediate value. In other cases, bit 0 of a word
- * in the heap is used to tag a pointer to a GLOC (VM global variable address)
- * or the header of a struct. But whenever an SCM variable holds a normal Scheme
- * value, bit 0 is 0.
+ * Non-immediates -- meaning that the variable holds a (possibly
+ * tagged) pointer into the cons pair heap.
+ *
+ * Non-objects are distinguished from other values by careful coding
+ * only (i.e., programmers must keep track of any SCM variables they
+ * create that don't contain ordinary scheme values).
+ *
+ * All immediates and non-immediates must have a 0 in bit 0. Only
+ * non-object values can have a 1 in bit 0. In some cases, bit 0 of a
+ * word in the heap is used for the GC tag so during garbage
+ * collection, that bit might be 1 even in an immediate or
+ * non-immediate value. In other cases, bit 0 of a word in the heap
+ * is used to tag a pointer to a GLOC (VM global variable address) or
+ * the header of a struct. But whenever an SCM variable holds a
+ * normal Scheme value, bit 0 is 0.
*
* Immediates and non-immediates are distinguished by bits two and four.
* Immediate values must have a 1 in at least one of those bits. Does
* this (or any other detail of tagging) seem arbitrary? Try changing it!
* (Not always impossible but it is fair to say that many details of tags
- * are mutually dependent).
- */
+ * are mutually dependent). */
#define SCM_IMP(x) (6 & (int)(x))
#define SCM_NIMP(x) (!SCM_IMP(x))
#define SCM_BOOL_T SCM_MAKIFLAG(17)
#define SCM_UNDEFINED SCM_MAKIFLAG(18)
#define SCM_EOF_VAL SCM_MAKIFLAG(19)
-#define SCM_UNUSED_NIL_VALUE SCM_MAKIFLAG(20)
+#define SCM_EOL SCM_MAKIFLAG(20)
#define SCM_UNSPECIFIED SCM_MAKIFLAG(21)