anchor.diff:  
   We propose that <<orderability-def>> and <<equivalence-def>> should be aligned with each other, i.e.
   
  -`expr1` is equivalent to `expr2` if and only if they have the same position under orderability (i.e. they would be sorted before (or after resp.) any other non-equivalent value in the same way).
  +`expr1` is equivalent to `expr2` if and only if they have the same position under orderability (i.e. they would be sorted before (or after respectively) any other non-equivalent value in the same way).
   
   Orderability and equivalence produce <<missing-null,"missing" `null` values>>.
   
  
positive.code: 
  == Proposal
  
  We propose to redefine <<comparability-def>> and <<equality-def>>, as well as <<orderability-def>> and <<equivalence-def>> as detailed in this section.
  
  [[concepts]]
  === Concepts
  
negative.code: 
  - <<comparability-equality,Comparability and equality>> are aligned with each other
    * <<equality-con,Equality>> follows natural, literal equality. However, values involving `null` are never equal to any other value. Nested structures are first tested for equality by shape (keys, size) and then their corresponding elements are tested for equality pairwise. This ensures that equality is compatible with interpreting `null` as "unknown" or "could be any value".
    * <<comparability-con,Comparability>> ensure that any two values of the same type in the <<global-sort-order>> are comparable.
    Two values of different types are incomparable and values involving `null` are incomparable, too.
    This ensures that `MATCH (n) WHERE n.prop < 42` will never find nodes where `n.prop` is of type `STRING`.
  - <<orderability-equivalence>> are aligned with each other
    * <<equivalence-con,Equivalence>> is a form of equality that treats `null` (and `NaN`) values as the same value. Equivalence is used in grouping and `DISTINCT` where `null` commonly is interpreted as a category marker for results with missing values instead of as a wildcard for any possible value.
    * <<orderability-con,Orderability>> follows comparability but additionally defines a <<global-sort-order>> between values of different types and is aligned with equivalence instead of equality, i.e. treats two `null` (respectively `NaN`) values as equivalent.
  - Aggregation functions that rely on notions of sameness and sorting are aligned with equivalence and orderability.
  
  [[examples]]
  