custom format spec

Author: willow-ahrens

README.md

@@ -15,10 +15,10 @@ Here is a table listing the current tensor frameworks that support the format:
 
 | Language | Framework | Status | Notes |
 | -------- | ------ | ------ | ----- |
-| C | [binsparse-reference-c](https://github.com/GraphBLAS/binsparse-reference-c) | under development | converts between binsparse V1.0 and custom in-memory sparse matrices |
-| C++ | [binsparse-reference-impl](https://github.com/GraphBLAS/binsparse-reference-impl) | under development | converts between binsparse V1.0 and custom in-memory sparse matrices | 
-| Julia | [Finch.jl](https://willowahrens.io/Finch.jl/dev/fileio/) | under development | converts between binsparse V1.0 and V2.0 and Finch matrices and tensors |
-| Python | [binsparse-python](https://github.com/ivirshup/binsparse-python) | under development | converts between binsparse V1.0 and scipy.sparse matrices |
+| C | [binsparse-reference-c](https://github.com/GraphBLAS/binsparse-reference-c) | under development | converts between binsparse and in-memory sparse matrices |
+| C++ | [binsparse-reference-impl](https://github.com/GraphBLAS/binsparse-reference-impl) | under development | converts between binsparse and in-memory sparse matrices | 
+| Julia | [Finch.jl](https://willowahrens.io/Finch.jl/dev/fileio/) | under development | converts between binsparse and Finch matrices and tensors, supports custom format spec |
+| Python | [binsparse-python](https://github.com/ivirshup/binsparse-python) | under development | converts between binsparse and scipy.sparse matrices |
 
 ### Editing
 

spec/latest/index.bs

@@ -274,10 +274,10 @@ Pairs must not be duplicated.
 
 Coordinate format is an alias for [[#coor_format]] format.
 
-### Version 2.0 only: Custom Formats ### {#custom_formats}
+### Custom Formats ### {#custom_formats}
 
-The contents of this section will be finalized with the release of Binsparse
-V2.0, and are subject to change until then.
+The contents of this section are optional for all parsers, but enable
+customizable sparse formats for matrices and tensors.
 
 Binsparse describes custom multidimensional formats hierarchically.  We can
 understand these formats as arrays of arrays, where the parent array and