Forked from open-telemetry/opentelemetry-go#5755 (comment)

When trying utf-8 support with OpenTelemetry, I found the default model.NameEscapingScheme of model.ValueEncodingEscaping surprising. It converted my metric name to U__rpc_2e_durations_2e_histogram_2e_seconds.

Underscore escaping is the most human-readable of the escaping schemes. For anyone using a system that doesn't support the new UTF-8 stuff, or even curl, being able to read the output or find/read the names when querying is probably more important. I also suspect, but haven't verified, that most existing escaping schemes replace with underscores (at least OpenCensus/OpenTelemetry currently do). If we defaulted to underscore replacement, it would make the migration easier on that front.

@ywwg