We present Dialog Moves Markup Language (DMML): an extensible markup language (XML) representation of modality independent communicative acts of automated conversational agents. In our architecture, DMML is the interface to and from conversational dialog managers for user interactions through any channel or modality. The use of a common XML interface language across different channels promotes high cost efficiency for the business. DMML itself has no application or domain specific elements; DMML elements embed elements representing ion business logic. DMML captures the abstractions necessary to represent arbitrary multi-agent dialogs and to build cost-efficient, sophisticated natural language dialog systems for business applications.