restrict schema coordinates to a unique grammar

Author: magicmark

spec/Appendix B -- Grammar Summary.md

@@ -43,14 +43,7 @@ Token ::
 - FloatValue
 - StringValue
 
-Punctuator ::
-
-- DotPunctuator
-- OtherPunctuator
-
-DotPunctuator :: `.` [lookahead != {`.`, Digit}]
-
-OtherPunctuator :: one of ! $ & ( ) ... : = @ [ ] { | }
+Punctuator :: one of ! $ & ( ) ... : = @ [ ] { | }
 
 Name ::
 
@@ -438,3 +431,6 @@ ArgumentCoordinate : Name . Name ( Name : )
 DirectiveCoordinate : @ Name
 
 DirectiveArgumentCoordinate : @ Name ( Name : )
+
+Note: This grammar is unique. A _schema coordinate_ may not include any other
+tokens.

spec/Section 2 -- Language.md

@@ -176,25 +176,12 @@ and is {Ignored}.
 
 ### Punctuators
 
-Punctuator ::
-
-- DotPunctuator
-- OtherPunctuator
-
-DotPunctuator :: `.` [lookahead != {`.`, Digit}]
-
-OtherPunctuator :: one of ! $ & ( ) ... : = @ [ ] { | }
+Punctuator :: one of ! $ & ( ) ... : = @ [ ] { | }
 
 GraphQL documents include punctuation in order to describe structure. GraphQL is
 a data description language and not a programming language, therefore GraphQL
 lacks the punctuation often used to describe mathematical expressions.
 
-The {`.`} punctuator must not be followed by a {`.`} or {Digit}. This ensures
-that the source {"..."} can only be interpreted as a single {`...`} and not
-three {`.`}. It also avoids any potential ambiguity with {FloatValue}. As an
-example the source {".123"} has no valid lexical representation (without this
-restriction it would have been interpreted as {`.`} followed by {IntValue}).
-
 ### Names
 
 Name ::

spec/Section 3 -- Type System.md

@@ -2248,6 +2248,9 @@ DirectiveCoordinate : @ Name
 
 DirectiveArgumentCoordinate : @ Name ( Name : )
 
+Note: A _schema coordinate_ is defined with its own grammar and may not include
+any other tokens.
+
 :: A _schema coordinate_ is a human readable string that uniquely identifies a
 _schema element_ within a GraphQL Schema.
 
@@ -2289,10 +2292,10 @@ production.
 
 The source text of a _schema coordinate_ is processed in the same way as that of
 a GraphQL document, as laid out in the [Language](#sec-Language) section, with
-the exception that {Ignored} tokens are disallowed. A schema coordinate must
-therefore not contain whitespace, line terminators, comments, commas, or a _Byte
-Order Mark_. This constraint ensures that schema coordinates are both
-unambiguous and unique.
+the exception that only the subset of tokens as described in the grammar above
+may be considered. A schema coordinate must therefore not contain whitespace,
+line terminators, comments, commas, or a _Byte Order Mark_. This constraint
+ensures that schema coordinates are both unambiguous and unique.
 
 **Resolving a Schema Coordinate**