diff --git a/libeos/command_line.py b/libeos/command_line.py
index 036d95e..949a5e6 100644
--- a/libeos/command_line.py
+++ b/libeos/command_line.py
@@ -154,18 +154,6 @@ def expand_file_list(short_notation):
     return sorted(file_list)
 
 
-def output_format_list(outputFormat):
-    format_list = []
-    if 'ort' in outputFormat or 'Rqz.ort' in outputFormat or 'Rqz' in outputFormat:
-        format_list.append('Rqz.ort')
-    if 'ort' in outputFormat or 'Rlt.ort' in outputFormat or 'Rlt' in outputFormat:
-        format_list.append('Rlt.ort')
-    if 'orb' in outputFormat or 'Rqz.orb' in outputFormat or 'Rqz' in outputFormat:
-        format_list.append('Rqz.orb')
-    if 'orb' in outputFormat or 'Rlt.orb' in outputFormat or 'Rlt' in outputFormat:
-        format_list.append('Rlt.orb')
-    return sorted(format_list, reverse=True)
-
 def command_line_options():
     clas   = commandLineArgs()
     update_loglevel(clas.verbose)
diff --git a/libeos/options.py b/libeos/options.py
index 1da52b7..83b7035 100644
--- a/libeos/options.py
+++ b/libeos/options.py
@@ -402,9 +402,20 @@ class ReductionConfig(ArgParsable):
                 },
             )
 
+class OutputFomatOption(StrEnum):
+    Rqz_ort = "Rqz.ort"
+    Rqz_orb = "Rqz.orb"
+    Rlt_ort = "Rlt.ort"
+    Rlt_orb = "Rlt.orb"
+    ort = "ort"
+    orb = "orb"
+    Rqz = "Rqz"
+    Rlt = "Rlt"
+
+
 @dataclass
 class OutputConfig(ArgParsable):
-    outputFormats: List[str] = field(
+    outputFormats: List[OutputFomatOption] = field(
             default_factory=lambda: ['Rqz.ort'],
             metadata={
                 'short': 'of',
@@ -429,6 +440,22 @@ class OutputConfig(ArgParsable):
                 },
             )
 
+    def _output_format_list(self, outputFormat):
+        format_list = []
+        if OutputFomatOption.ort in outputFormat or OutputFomatOption.Rqz_ort in outputFormat or OutputFomatOption.Rqz in outputFormat:
+            format_list.append(OutputFomatOption.Rqz_ort)
+        if OutputFomatOption.ort in outputFormat or OutputFomatOption.Rlt_ort in outputFormat or OutputFomatOption.Rlt in outputFormat:
+            format_list.append(OutputFomatOption.Rlt_ort)
+        if OutputFomatOption.orb in outputFormat or OutputFomatOption.Rqz_orb in outputFormat or OutputFomatOption.Rqz in outputFormat:
+            format_list.append(OutputFomatOption.Rqz_orb)
+        if OutputFomatOption.orb in outputFormat or OutputFomatOption.Rlt_orb in outputFormat or OutputFomatOption.Rlt in outputFormat:
+            format_list.append(OutputFomatOption.Rlt_orb)
+        return sorted(format_list, reverse=True)
+
+    def __post_init__(self):
+        self.outputFormats = self._output_format_list(self.outputFormats)
+
+
 # ===================================
 
 @dataclass