This ordering relation for qualitative values indicates that the subject is greater than or equal to the object.

This ordering relation for qualitative values indicates that the subject is greater than the object.

Identifies the volume of publication or multi-part work; for example, "iii" or "2".

Identifies the issue of publication; for example, "iii" or "2".

A broadcast service associated with the publication event.

A flag to signal that the item, event, or place is accessible for free.

A secondary value that provides additional information on the original value, e.g. a reference temperature or a type of measurement.

The value of a [QuantitativeValue](https://schema.org/QuantitativeValue) (including [Observation](https://schema.org/Observation)) or property value node. - For [QuantitativeValue](https://schema.org/QuantitativeValue) and [MonetaryAmount](https://schema.org/MonetaryAmount), the recommended type for values is 'Number'. - For [PropertyValue](https://schema.org/PropertyValue), it can be 'Text', 'Number', 'Boolean', or 'StructuredValue'. - Use values from 0123456789 (Unicode 'DIGIT ZERO' (U+0030) to 'DIGIT NINE' (U+0039)) rather than superficially similar Unicode symbols. - Use '.' (Unicode 'FULL STOP' (U+002E)) rather than ',' to indicate a decimal point. Avoid using these symbols as a readability separator.

A string or text indicating the unit of measurement. Useful if you cannot provide a standard unit code for [unitCode](https://schema.org/unitCode).

The unit of measurement given using the UN/CEFACT Common Code (3 characters) or a URL. Other codes than the UN/CEFACT Common Code may be used with a prefix followed by a colon.

A commonly used identifier for the characteristic represented by the property, e.g. a manufacturer or a standard code for a property. propertyID can be (1) a prefixed string, mainly meant to be used with standards for product properties; (2) a site-specific, non-prefixed string (e.g. the primary key of the property or the vendor-specific ID of the property), or (3) a URL indicating the type of the property, either pointing to an external vocabulary, or a Web resource that describes the property (e.g. a glossary entry). Standards bodies should promote a standard prefix for the identifiers of properties from their standards.

The lower value of some characteristic or property.

The upper value of some characteristic or property.

The program providing the membership. It is preferable to use [:program](https://schema.org/program) instead.

A unique identifier for the membership.

The Organization (airline, travelers' club, retailer, etc.) the membership is made with or which offers the MemberProgram.

A pointer from a newer variant of a product to its previous, often discontinued predecessor.

A pointer from a previous, often discontinued variant of the product to its newer variant.

Indicates the kind of product that this is a variant of. In the case of [ProductModel](https://schema.org/ProductModel), this is a pointer (from a ProductModel) to a base product from which this product is a variant. It is safe to infer that the variant inherits all product features from the base model, unless defined locally. This is not transitive. In the case of a [ProductGroup](https://schema.org/ProductGroup), the group description also serves as a template, representing a set of Products that vary on explicitly defined, specific dimensions only (so it defines both a set of variants, as well as which values distinguish amongst those variants). When used with [ProductGroup](https://schema.org/ProductGroup), this property can apply to any [Product](https://schema.org/Product) included in the group.

The release date of a product or product model. This can be used to distinguish the exact variant of a product.

The date the item, e.g. vehicle, was purchased by the current owner.

The date of production of the item, e.g. vehicle.

The product identifier, such as ISBN. For example: `meta itemprop="productID" content="isbn:123-456-789"`.

The model of the product. Use with the URL of a ProductModel or a textual representation of the model identifier. The URL of the ProductModel can be from an external source. It is recommended to additionally provide strong product identifiers via the gtin8/gtin13/gtin14 and mpn properties.