diff --git a/src/odr/file.hpp b/src/odr/file.hpp
index e3e28f4d..1070340f 100644
--- a/src/odr/file.hpp
+++ b/src/odr/file.hpp
@@ -97,6 +97,19 @@ enum class FileLocation {
   disk,
 };
 
+/// @brief Collection of decoder engines.
+enum class DecoderEngine {
+  odr,
+  pdf2html_ex,
+  wv_ware,
+};
+
+/// @brief Preference for decoding files.
+struct DecodePreference final {
+  std::vector<FileType> file_type_priority;
+  std::vector<DecoderEngine> engine_priority;
+};
+
 /// @brief Collection of encryption states.
 enum class EncryptionState {
   unknown,
diff --git a/src/odr/internal/open_strategy.hpp b/src/odr/internal/open_strategy.hpp
index 1661cd0e..a18cef8a 100644
--- a/src/odr/internal/open_strategy.hpp
+++ b/src/odr/internal/open_strategy.hpp
@@ -6,7 +6,9 @@
 
 namespace odr {
 enum class FileType;
-}
+enum class DecoderEngine;
+struct DecodePreferences;
+} // namespace odr
 
 namespace odr::internal::abstract {
 class File;
@@ -20,11 +22,22 @@ class Path;
 
 namespace odr::internal::open_strategy {
 std::vector<FileType> types(std::shared_ptr<internal::abstract::File> file);
+std::vector<DecoderEngine>
+engines(std::shared_ptr<internal::abstract::File> file, FileType as);
 
 std::unique_ptr<internal::abstract::DecodedFile>
 open_file(std::shared_ptr<internal::abstract::File> file);
 std::unique_ptr<internal::abstract::DecodedFile>
 open_file(std::shared_ptr<internal::abstract::File> file, FileType as);
+std::unique_ptr<internal::abstract::DecodedFile>
+open_file(std::shared_ptr<internal::abstract::File> file, FileType as,
+          DecoderEngine with);
+std::unique_ptr<internal::abstract::DecodedFile>
+open_file(std::shared_ptr<internal::abstract::File> file,
+          const DecodePreferences &preferences);
+std::unique_ptr<internal::abstract::DecodedFile>
+open_file(std::shared_ptr<internal::abstract::File> file, FileType as,
+          const DecodePreferences &preferences);
 
 std::unique_ptr<internal::abstract::DocumentFile>
 open_document_file(std::shared_ptr<internal::abstract::File> file);