A method of associating a content object with metadata uses a combination of a content identifier and a bounding identifier to enable handling of disparate sets of content identifiers for content objects with potentially conflicting content identifiers. The method receives a content identifier for a content object from among a set of content identifiers. It provides a unique bounding identifier for the set of content identifiers. This unique bounding identifier is used in combination with the content identifier to form a globally unique identifier for the content object. This globally unique identifier is associated with a metadata source, which enables routing of a user to the metadata source. Another novel method addresses content objects with two or more content identifiers, potentially referencing different metadata sources. This method registers different globally unique identifiers for a content object. These globally unique identifiers each comprise a content identifier provided with the content object and a bounding identifier identifying a set of content identifiers of which the content identifier is a member. For each of the globally unique identifiers, information is maintained about a metadata source. The method receives a first content identifier for the content object, and uses a bounding identifier associated with the set of the first content identifier to determine the globally unique identifier for the first content identifier. The user is routed to the metadata source associated with globally unique identifier. This document describes a novel system that enables multiple identity providers (ID Providers) to register and use the system. The ID Provider registers with a metadata directory system, receives a unique bounding identifier, and uses this bounding ID (e.g., an ID provider ID) with subsequent interactions with the metadata directory system. Separately, metadata source providers register metadata sources with the metadata directory system. This enables many different participants to associate content objects with metadata sources using one or more identify providers. Examples of metadata source providers include content providers, like content owners or retailers that have the flexibility of working with different ID providers to associate content objects with metadata. Both content providers and ID providers can register and use the system. The metadata source is the system or device that provides the metadata, like a web site. The directory system uses an identifier for the metadata source, which enables it to maintain an association between a content object and its corresponding metadata source. For example, in some embodiments, a URL serves to identify the location of the source. The Content Metadata Directory Services (CMDS) is a global trusted directory service that connects consumers of identified content to content-provider authorized and managed metadata databases and other digital resources. It includes mostly links to metadata, forms globally unique IDs based upon overlapping content identifiers and unique bounding identifiers, enables multiple content identifiers within a content object, and enables multiple content identity technology providers, even when they are using different technology.