GBFS' reference - timezones: clarifications needed on deprecated/link/aliases time zones

[Oxalin]

Hi. I've been encountering some GBFS feeds containing non canonical timezones, i.e. America/Montreal. GBFS' reference v3.0 points to the Wiki tz database time zones website, which lists canonical time zones along with links/aliases AND time zones that were canonical but deprecated (now being links). GBFS' reference doesn't specify if links/aliases are supported.

As you may know, the IANA provides a list of canonical time zones. It also maintains a backward file containing deprecated time zones and aliases. This file suggests to include the list for compatibility reasons.

The Canonical GBFS validator schemas enumerate the values supported by the validator for different spec versions. Since it is the Canonical GBFS validator, I would expect the lists to only contain canonical values or, otherwise, to accept all the values including the one in the backward list (which isn't the case for any of these situations). Values like "CST6CDT" that are links (deprecated from canonical time zones) can still be found in the schemas.

This situation creates confusion and raises questions:

• Should the Canonical validator only validate timezone values that are canonical at the time of the release of the specs? If so, non canonical values should be removed.
• Should deprecated canonical values be supported? This list can change yearly for political reasons and users may end up expecting a timezone value that was canonical to still be present. Not all developers are following the latest list and some applications generating GBFS feeds may not be updated.
• Should links/aliases that have never been canonical be supported?
• Why would a some deprecated/link timezones be valid ("CST6CDT" for example), but not others? How is this decided?
• How should the specifications clarify this situation?