Permit non-alphabetic characters as the 1st character in metric names

[heyams]

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/api.md#instrument-name-syntax

We are looking to start using a dotnet OpenTelemetry distribution. Unfortunately, our metric names begin with a '-' character, which is not allowed as the first character.

Changing the metric names is not a feasible option for us due to the high cost and the potential invalidation of numerous queries accumulated across various tools, dashboards, and users. Therefore, we hope that a feature request could be considered to allow non-alphabetic characters as the first character of metric names. This would enable us to fully utilize the features and benefits provided by OpenTelemetry metrics.

Thanks,
Helen

[regexrowboat]

👍

[svrnm]

hey thanks for your proposal, this needs a broader discussion, I recommend that you attend the SIG meeting to get some feedback: https://github.com/open-telemetry/community/?tab=readme-ov-file#specification-sigs

[cijothomas]

Previous relevant Issue/PR that removed some restriction on metric name : #3422

This keeps coming up. "/" is now allowed, but there are asks to support longer-than-63 length, ":", " " (space). And this issue which is asking to relax 1st character restriction.

Will join the next Spec SIG meeting to discuss how to unblock users.