diff --git a/src/pymovements/dataset/.dataset_definition.py.swp b/src/pymovements/dataset/.dataset_definition.py.swp
new file mode 100644
index 00000000..2795a03c
Binary files /dev/null and b/src/pymovements/dataset/.dataset_definition.py.swp differ
diff --git a/src/pymovements/datasets/didec.py b/src/pymovements/datasets/didec.py
index b9ead4c6..c27faddc 100644
--- a/src/pymovements/datasets/didec.py
+++ b/src/pymovements/datasets/didec.py
@@ -47,6 +47,10 @@ class DIDEC(DatasetDefinition):
     name: str
         The name of the dataset.
 
+    has_files: dict[str, bool]
+        Indicate whether the dataset contains 'gaze', 'precomputed_events', and
+        'precomputed_reading_measures'.
+
     mirrors: dict[str, tuple[str, ...]]
         A tuple of mirrors of the dataset. Each entry must be of type `str` and end with a '/'.
 
@@ -59,6 +63,9 @@ class DIDEC(DatasetDefinition):
     experiment: Experiment
         The experiment definition.
 
+    extract: dict[str, bool]
+        Decide whether to extract the data.
+
     filename_format: dict[str, str]
         Regular expression which will be matched before trying to load the file. Namedgroups will
         appear in the `fileinfo` dataframe.
@@ -67,6 +74,27 @@ class DIDEC(DatasetDefinition):
         If named groups are present in the `filename_format`, this makes it possible to cast
         specific named groups to a particular datatype.
 
+    trial_columns: list[str]
+            The name of the trial columns in the input data frame. If the list is empty or None,
+            the input data frame is assumed to contain only one trial. If the list is not empty,
+            the input data frame is assumed to contain multiple trials and the transformation
+            methods will be applied to each trial separately.
+
+    time_column: str
+        The name of the timestamp column in the input data frame. This column will be renamed to
+        ``time``.
+
+    time_unit: str
+        The unit of the timestamps in the timestamp column in the input data frame. Supported
+        units are 's' for seconds, 'ms' for milliseconds and 'step' for steps. If the unit is
+        'step' the experiment definition must be specified. All timestamps will be converted to
+        milliseconds.
+
+    pixel_columns: list[str]
+        The name of the pixel position columns in the input data frame. These columns will be
+        nested into the column ``pixel``. If the list is empty or None, the nested ``pixel``
+        column will not be created.
+
     column_map: dict[str, str]
         The keys are the columns to read, the values are the names to which they should be renamed.
 
@@ -122,8 +150,6 @@ class DIDEC(DatasetDefinition):
         },
     )
 
-    extract: dict[str, bool] = field(default_factory=lambda: {'gaze': True})
-
     experiment: Experiment = Experiment(
         screen_width_px=1680,
         screen_height_px=1050,
@@ -134,6 +160,8 @@ class DIDEC(DatasetDefinition):
         sampling_rate=1000,
     )
 
+    extract: dict[str, bool] = field(default_factory=lambda: {'gaze': True})
+
     filename_format: dict[str, str] = field(
         default_factory=lambda: {
             'gaze':