Version 2.1.1

This version is backwards compatible back to 2.0.0.

All updates to the spec between release 2.1.0 and 2.1.1 can be seen here:
v2.1.0...v2.1.1

There are three minor documentation clarifications, as described in the changelog:

1. clarified how to indicate a dimensionless quantity within an array of units for an array-valued parameter with non-uniform units; see Issue #85
2. clarified the use of scalar and array values for labels and units that describe an array-valued parameter; see Issue #91
3. clarified that null is not allowed as a value within a centers or ranges array in a bins description; see Issue #86

Version 2.1.0

This version is backwards compatible with 2.0.0.

All updates to the spec between release 2.0 and 2.1 can be seen here:
v2.0.0...v2.1.0
(This may include a few small commits after the actual release.)

From the changelog:

Documentation

1. replaced "hapi-server.org" with just "server" in URLs
2. clarified what the length attribute means for data parameters
3. clarified how to specify array sizes when one array dimension size is 1
4. more clarification and examples for error messages from HAPI servers
5. fixed multiple typos and made wording improvements

Schema

1. changed the definition of 'units' to allow for different units in the elements of an array
2. changed the definition of 'label' to allow for different labels for each element in the array
3. deprecated the use of all uppercase for the time stamp location options in favor of all lowercase, which is more consistent with the rest of the specification
4. now allow multi-dimensional data to not have bins in every dimension; any dimension with null for 'centers' and nothing present for 'ranges' will have no bin definition in that dimension

Server API

1. add HAPI 1411 error out of order or duplicate parameters
2. clarified server responses when time range has no data (HTTP status of 200 and HAPI status of 1201 and return no data content) or data is all fill (HTTP status of 200 and HAPI status of 1200 and return the fill values)

Version 2.0.0

Here are the changes from v1.0.0:

1. time values output by the server now must end with "Z"
2. the "units" on the bins are required
3. incoming time values should have a trailing "Z" to indicate GMT+0, but are interpreted as such even if there is no trailing Z
4. the length value for strings is now consistently described; all unused characters in the string should be filled with null characters (so no null terminator is needed if the string is exactly the given length)
5. in CSV output, the use of quotes for string values with commas is clarified
6. the subset of ISO8601 that we use is better described

Note that items 1 and 2 introduce changes that are not backwards compatible, as indicated by the new major version number.

Version 1.1.0

ready for general use;
updates include: status objects, clarification of bins, provisional support for 2-D or higher arrays, changes to a few metadata keywords

Version 1.0

Initial release.