Reserved Names

Validation Rules documents define a set of reserved names with predefined semantics. These names are interpreted specially by validators and must not be used as regular configuration or rule identifiers.

All reserved names start with the prefix vr_.

Design Rationale

Reserved names are used instead of extending the ELCL language with additional meta-syntax. While both approaches are viable, the prefix-based solution keeps parser implementations simpler, avoids grammar extensions, and reduces overall implementation effort.

Rules for Reserved Names

1. Prefix Requirement: All reserved names must start with the prefix vr_.

   [vr_template.interface]
   type: "section"
   
   [.address]
   type: "text"
   default: "localhost"
   
   [.protocol]
   type: "text"
   default: "https"
   

2. All Names with Prefix Are Reserved: Any name that starts with vr_ is considered reserved, regardless of whether it has an explicitly defined meaning in this specification.

   Validators must reject the use of unknown reserved names.

   [settings.vr_headset]  # ERROR: unknown reserved name.
   type: "text"
   

3. Escaping Reserved Names: Regular names that would otherwise be interpreted as reserved can be escaped by prefixing them with vr_vr_.

   During normalization, the leading escape prefix is removed and the name is treated as a regular identifier.

   [settings.vr_vr_headset]  # Defines rules for settings.vr_headset
   type: "text"
   

List of Reserved Names

The following table lists all reserved names defined by this specification.

Reserved Name	Description
vr_template	Section defined at the document root that provides reusable templates for node-rules definitions.
vr_any	Matches arbitrary child names under a section.
vr_name	Subsection of vr_any that defines constraints for the names themselves.
vr_entry	Subsection of a section list, value list, or value matrix definition that defines the node-rules for each entry.
vr_key	Section list defined at the document root or inside node-rules definitions to declare unique keys and create indexes for use with key constraints.
vr_dependency	Subsection of a node-rules definition that declares dependencies between child nodes.
vr_vr_*	Escape prefix used to define regular names that would otherwise be interpreted as reserved.