Update doc/USAGE

wording, bs trim

doc/USAGE

@@ -92,7 +92,7 @@ at that key followed by the data beneath its child enfilade.
 6. A KEY MAY HAVE BOTH A DATUM AND CHILDREN
 --------------------------------------------
 
-This is important.
+In cases where,
 
     (enfilade-put-data e "1.2" 99)
     (enfilade-put-data e "1.2.5" 50)
@@ -197,33 +197,7 @@ Subtract / difference:
 These are the historical tumbler operations, not ordinary decimal-number
 addition and subtraction.
 
-11. WHY THIS MATTERS FOR ZIGZAG
--------------------------------
-
-An enfilade does not need to understand what a datum means.
-
-That is useful when the datum is a ZigZag cell pointer.
-
-Conceptually:
-
-    cell ID
-      |
-      v
-    tumbler
-      |
-      v
-    enfilade
-      |
-      v
-    cell
-
-The catalogue can therefore answer:
-
-    “What cell is stored at this ID?”
-
-without embedding ZigZag cell structure into the indexing mechanism.
-
-12. THE C VERSION
+11. THE C VERSION
 -----------------
 
 Include:
@@ -256,7 +230,7 @@ The important rule is therefore:
     the enfilade owns its tree;
     the caller owns its datum.
 
-13. TUMBLER C API
+12. TUMBLER C API
 -----------------
 
 Include:
@@ -289,7 +263,7 @@ also release:
     tumbler_free(&b);
     tumbler_free(&out);
 
-14. VALID TUMBLERS
+13. VALID TUMBLERS
 ------------------
 
 The current C representation accepts one or more unsigned decimal fields:
@@ -313,7 +287,7 @@ The zero field is legal.  Historical Xanadu addressing uses zero fields as
 delimiters in some larger address formats; this small enfilade does not assign
 zero any additional structural meaning.
 
-15. ERRORS
+14. ERRORS
 ----------
 
 Malformed tumbler text:
@@ -336,7 +310,7 @@ Allocation failure:
 --------------------------------------
 
 You do not need CRUM, POOM, Granfilade, Spanfilade, WID, DISP, orgl, loaf, or
-Green's virtual-memory machinery to use this object.
+Udanax Green's virtual-memory machinery to use this object.
 
 Those names describe the larger historical system and specialized data
 structures built around enfilades.  They are important when implementing those
@@ -347,7 +321,7 @@ The right mental model for this package is simply:
 
     tumbler -> path through an enfilade -> datum(s)
 
-17. REFERENCES
+15. REFERENCES
 --------------
 
 Immediate behavioral reference: