diff --git a/DataGuide_AAPF_HSI.md b/DataGuide_AAPF_HSI.md
index 291d6c4..6229a4a 100644
--- a/DataGuide_AAPF_HSI.md
+++ b/DataGuide_AAPF_HSI.md
@@ -64,37 +64,34 @@ This document details the file system organization and navigation procedures for
 
 ### How to Read Information in Header Summary (header_summary_plants.csv, header_summary_ref.csv)
 
-| Column Head          | Description                                           |
-|----------------------|-------------------------------------------------------|
-| `header path`        | File path to the header file                          |
-| `camera model`       | Camera mode                                           |
-| `serial number`      | Serial number of the camera                           |
-| `roi left`           | Camera- and height-specific parameter, not relevant to vegetation segments         |
-| `roi top`            | Camera- and height-specific parameter, not relevant to vegetation segments         |
-| `roi width`          | Camera- and height-specific parameter, not relevant to vegetation segments         |
-| `roi height`         | Camera- and height-specific parameter, not relevant to vegetation segments         |
-| `samples`            | Width of data cube (conveyer belt direction)          |
-| `bands`              | Number of spectral channels                           |
-| `lines`              | Number of scanslines from top to bottom               |
-| `scanStartTime`      | Scan start time                                       |
-| `scanEndTime`        | Scan end time                                         |
-| `Wavelength`         | List of central wavelengths for each channel (separated by "\|")         |
-| `fwhm`               | Full wavelength at half maximum (width of wavelengths, separated by "\|" |
-| `PlantID`            | Plant ID (POT_BARCODE)     |
-| `CarrierID`          ||
-| `PlantHeight`||
-| `PlantWidth`||
-| `LotID`||
-| `CameraPosition`||
-| `illumination`||
-| `scandir` ||
-| `scan_order`||
-| `dark white`||
-
-
-
-
-
+The definition of column headers and corresponding values mostly originates from the sensor vendor and system integrator.
+
+| Column Head          | Description                                                                                     |
+|----------------------|-------------------------------------------------------------------------------------------------|
+| `header path`        | File path to the header file                                                                    |
+| `camera model`       | Camera mode                                                                                     |
+| `serial number`      | Serial number of the camera                                                                     |
+| `roi left`           | Camera- and height-specific parameter, not relevant to vegetation segments                      |
+| `roi top`            | Camera- and height-specific parameter, not relevant to vegetation segments                      |
+| `roi width`          | Camera- and height-specific parameter, not relevant to vegetation segments                      |
+| `roi height`         | Camera- and height-specific parameter, not relevant to vegetation segments                      |
+| `samples`            | Width of data cube (conveyer belt direction)                                                    |
+| `bands`              | Number of spectral channels                                                                     |
+| `lines`              | Number of scanslines from top to bottom                                                         |
+| `scanStartTime`      | Scan start time                                                                                 |
+| `scanEndTime`        | Scan end time                                                                                   |
+| `Wavelength`         | List of central wavelengths for each channel (separated by "\|")                                |
+| `fwhm`               | Full wavelength at half maximum (width of wavelengths, separated by "\|"                        |
+| `PlantID`            | Plant ID (POT_BARCODE)                                                                          |
+| `CarrierID`          | System-generated carrier ID                                                                     |
+| `PlantHeight`        | Plnat height (❗ calculation method unclear)                                                    |
+| `PlantWidth`         | Plant width (❗ calculation method unclear)                                                     |
+| `LotID`              | Experiment ID                                                                                   |
+| `CameraPosition`     | The value in this column is set to "Both" when data from the corresponding opposing viewpoint (top for side views, side for top view) is also available. (Verification pending) |
+| `illumination`       | "4" under normal illumination conditions (no malfunction)                                       |
+| `specdir`            | Spectral range of the camera and viewing direction (VNIR-SIDE, VNIR-TOP, SWIR-SIDE, or SWIR-TOP)|
+| `scan_order`         | The 'Scan order' column assigns a unique integer value to each scan incrementally based on the order of image capture during the experiment within the AAPF. This value is identical for all cameras (VNIR-SIDE, VNIR-TOP, SWIR-SIDE, and SWIR-TOP) operating concurrently during a single scanning session, which captures data for the same plant on the same day |
+| `dark white`         | "Dark" or "White", only available for `header_summary_ref.csv`                                  |
 
 ### How to Read Animated GIF Files Containing VNIR-SWIR Coregistration Quality Info