Foreigners with a residence permit or a document of equal standing issued by a member state of the Schengen Agreement, including Latvia, can travel freely in the territory of the Schengen Agreement member states for a time period not exceeding three months in any half year, as long as the foreigners are eligible under the requirements of Article 5 of the Schengen Borders Code:    

• they have valid travel document
• they can provide a reason for the planned stay and its conditions
• they can provide evidence of subsistence for the planned period of stay and for the return to their home state
• they have not been reported in the Schengen Information System as being barred by a member state of the Schengen Agreement from entering the whole of the Schengen area
• they are not considered a threat to the politics, internal security, public health, or international relations of a member state of the Schengen Agreement

Each Schengen Agreement member state decides on its own, with which documents issued by it, a person may travel to other member states. Information on these documents is included in Annex 4 List of documents entitling holders to entry without a visa of the instructions Common consular instructions on visas for the diplomatic missions and consular posts (see web site The access to European Union law).  

If it is not clear, whether a specific document grants such rights, one should consult the immigration institutions of his home state.