What does a single exclamation mark do in YAML?
I'm working with the YamlDotNet library and I'm getting this error when loading a YAML file: While parsing a tag, did not find expected tag URI. The YAML file is supposed to be well-formed because it comes right from RoR . The error seems to be triggered by this code: formats: default: ! '%d-%m-%Y' long: ! '%d %B, %Y' short: ! '%d %b' I'm not an expert, but I see from the YAML spec that you can use an exclamation mark to indicate a custom object/type, and two exclamation marks to indicate an explicit built-in type. obj1: !custom # whatever obj2: !!str "My string" However I haven't been able to