A (subscription model) may be used in a context of instant messaging.Logical formLearned from2 sentences. Notifications can be for a duration of a subscription.Logical formLearned from2 sentences. An attribute may pertain-to a (subscription object).Logical formLearned from2 sentences. 7.8.xes may undergo a (subscription property).Logical formLearned from2 sentences. A subscription may be established.Logical formLearned from2 sentences. Subscriptions can be to a multiplicity of documents.Logical formLearned from2 sentences. A server may generate a series of subscriptions.Logical formLearned from2 sentences. A duration of a subscription may correspond in a way to a period.Logical formLearned from2 sentences. A registration may be followed by a subscription.Logical formLearned from2 sentences. A subscription can be for a resource.Logical formLearned from2 sentences. Subscriptions may be authenticated.Logical formLearned from2 sentences. A subscription can be unauthorized.Logical formLearned from2 sentences. A subscription may have a (persistence indicator).Logical formLearned from2 sentences. Subscriptions can be arbitrary.Logical formLearned from2 sentences. Subscriptions to an (event package) may be authenticated.Logical formLearned from2 sentences.