At a high level, value forms allow the specification of a "replaces"/"replacement" pair to also apply to other ways the "replaces" value may have been specified in the source by specifying a transform from the original value of "replaces" in configuration to the one that may be found in the source.

Example

In my source, the value "Hi there" should be replaced by a user supplied value, but, "Hi there" should be as well. The user value should be XML encoded for the latter and not for the former. The below snippet from template.json shows how to accomplish this.

{
  ...
  "symbols": {
    "example": {
      "type": "parameter",
      "dataType": "string",
      "replaces": "\"Hi there\"",
      "forms": {
        "global": [ "encode" ]
      }
    }
  },
  "forms": {
    "encode": {
      "identifier": "xmlEncode"
    }
  }
}

The forms section (peer to symbols) defines the set of transforms that can be referenced by symbol definitions. In the symbol called example, the entry from the forms section is referenced for all file patterns (the property global indicates that the transform should be included everywhere).

When the value say, Test © is supplied as the value for the parameter example, two replacements get set up:

1. "Hi There" -> Test ©
2. "Hi There" -> Test ©

replace - Performs a replacement with regular expressions

"forms": {
    "dotToUnderscore": {
      "identifier": "replace",
      "pattern": "\\.",        // A regular expression matching the characters to replace
      "replacement": "_"       // The replacement for the matched characters
    }
}

chain - Performs multiple transformations

"forms": {
    "chained": {
      "identifier": "chain",
      "steps": [ "dotToUnderscore", "digitToBang" ]  // An array of names of other transformations (applied in the order they appear in the array)
    },
}

xmlEncode - XML encodes a value

"forms": {
    "encode": {
      "identifier": "xmlEncode"
    }
}

lowerCase - Converts the letters of the value to lowercase using the casing rules of the current culture.

"forms": {
    "lc": {
      "identifier": "lowerCase"
    }
}

lowerCaseInvariant - Converts the letters of the value to lowercase using the casing rules of the invariant culture.

"forms": {
    "lc": {
      "identifier": "lowerCaseInvariant"
    }
}

upperCase - Converts the letters of the value to uppercase using the casing rules of the current culture.

"forms": {
    "uc": {
      "identifier": "upperCase"
    }
}

upperCaseInvariant - Converts the letters of the value to uppercase using the casing rules of the invariant culture.

"forms": {
    "uc": {
      "identifier": "upperCaseInvariant"
    }
}

firstLowerCase - Converts the first letter of the value to lowercase using the casing rules of the current culture. Available since .NET 5.0.300.

"forms": {
    "first_lc": {
      "identifier": "firstLowerCase"
    }
}

firstLowerCaseInvariant - Converts the first letter of the value to lowercase using the casing rules of the invariant culture. Available since .NET 5.0.300.

"forms": {
    "first_lc": {
      "identifier": "firstLowerCaseInvariant"
    }
}

firstUpperCase - Converts the first letter of the value to uppercase using the casing rules of the current culture. Available since .NET 5.0.300.

"forms": {
    "first_uc": {
      "identifier": "firstUpperCase"
    }
}

firstUpperCaseInvariant - Converts the first letter of the value to uppercase using the casing rules of the invariant culture. Available since .NET 5.0.300.

    "forms": {
        "first_uc": {
          "identifier": "firstUpperCaseInvariant"
        }
    }

titleCase - Converts the value to title case using the casing rules of the current culture. See TextInfo.ToTitleCase(String) documentation for more details. Available since .NET 5.0.300.

"forms": {
    "title": {
      "identifier": "titleCase"
    }
}

kebabCase - Converts the value to kebab case using the casing rules of the invariant culture. Available since .NET 5.0.300.

"forms": {
    "kebab": {
      "identifier": "kebabCase"
    }
}