Talk about "consuming input", not "advancing parser position"

It's shorter, less technical, and more understandible.

README.md

@@ -304,13 +304,12 @@ backtracking.
 #### & *expression*
 
 Try to match the expression. If the match succeeds, just return `undefined` and
-do not advance the parser position, otherwise consider the match failed.
+do not consume any input, otherwise consider the match failed.
 
 #### ! *expression*
 
 Try to match the expression. If the match does not succeed, just return
-`undefined` and do not advance the parser position, otherwise consider the match
-failed.
+`undefined` and do not consume any input, otherwise consider the match failed.
 
 #### & { *predicate* }
 
@@ -318,8 +317,8 @@ The predicate is a piece of JavaScript code that is executed as if it was inside
 a function. It gets the match results of labeled expressions in preceding
 expression as its arguments. It should return some JavaScript value using the
 `return` statement. If the returned value evaluates to `true` in boolean
-context, just return `undefined` and do not advance the parser position;
-otherwise consider the match failed.
+context, just return `undefined` and do not consume any input; otherwise
+consider the match failed.
 
 The code inside the predicate can access all variables and functions defined in
 the initializer at the beginning of the grammar.
@@ -347,8 +346,8 @@ The predicate is a piece of JavaScript code that is executed as if it was inside
 a function. It gets the match results of labeled expressions in preceding
 expression as its arguments. It should return some JavaScript value using the
 `return` statement. If the returned value evaluates to `false` in boolean
-context, just return `undefined` and do not advance the parser position;
-otherwise consider the match failed.
+context, just return `undefined` and do not consume any input; otherwise
+consider the match failed.
 
 The code inside the predicate can access all variables and functions defined in
 the initializer at the beginning of the grammar.

spec/behavior/generated-parser-behavior.spec.js

@@ -268,7 +268,7 @@ describe("generated parser behavior", function() {
           expect(parser).toParse("a", "a");
         });
 
-        it("advances parse position past the matched text", function() {
+        it("consumes the matched text", function() {
           var parser = PEG.buildParser('start = "a" .', options);
 
           expect(parser).toParse("ab");
@@ -341,7 +341,7 @@ describe("generated parser behavior", function() {
           expect(parser).toParse("a", "a");
         });
 
-        it("advances parse position past the matched character", function() {
+        it("consumes the matched character", function() {
           var parser = PEG.buildParser('start = [a] .', options);
 
           expect(parser).toParse("ab");
@@ -377,7 +377,7 @@ describe("generated parser behavior", function() {
           expect(parser).toParse("a", "a");
         });
 
-        it("advances parse position past the matched character", function() {
+        it("consumes the matched character", function() {
           var parser = PEG.buildParser('start = . .', options);
 
           expect(parser).toParse("ab");