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: ==== Orderability ====
  
  [[global-sort-order,global sort order]]
  We propose that orderability be defined between any pair of values such that the result is always `true` or `false`.
  
  To accomplish this, we propose a pre-determined order of types and ensure that each value falls under exactly one disjoint type in this order.
  We define the following ascending global sort order of disjoint types:
  
  * `MAP` types
  ** <<regular-map,Regular map>>
  