The 4.Evaluation part of the previous reference, starting with 'If the currently referenced value is a JSON array, the reference token MUST contain either...' is not implemented.
**err.Value()**: *interface{}* Returns the value given
**err.Context()**: *gojsonschema.jsonContext* Returns the context. This has a String() method that will print something like this: (root).firstName
**err.Field()**: *string* Returns the fieldname in the format firstName, or for embedded properties, person.firstName. This returns the same as the String() method on *err.Context()* but removes the (root). prefix.
**err.Description()**: *string* The error description. This is based on the locale you are using. See the beginning of this section for overwriting the locale with a custom implementation.
**err.Details()**: *gojsonschema.ErrorDetails* Returns a map[string]interface{} of additional error details specific to the error. For example, GTE errors will have a "min" value, LTE will have a "max" value. See errors.go for a full description of all the error details. Every error always contains a "field" key that holds the value of *err.Field()*
Note in most cases, the err.Details() will be used to generate replacement strings in your locales. and not used directly i.e.
```
%field% must be greater than or equal to %min%
```
## Formats
JSON Schema allows for optional "format" property to validate strings against well-known formats. gojsonschema ships with all of the formats defined in the spec that you can use like this:
````json
{"type":"string","format":"email"}
````
Available formats: date-time, hostname, email, ipv4, ipv6, uri.
For repetitive or more complex formats, you can create custom format checkers and add them to gojsonschema like this:
```go
// Define the format checker
typeRoleFormatCheckerstruct{}
// Ensure it meets the gojsonschema.FormatChecker interface
