diff --git a/DataGuide_AAPF_HSI.md b/DataGuide_AAPF_HSI.md
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--- a/DataGuide_AAPF_HSI.md
+++ b/DataGuide_AAPF_HSI.md
@@ -1,11 +1,21 @@
 # DataGuide-AAPF-HSI
 
-This document details the file system organization and navigation procedures for accessing both unprocessed hyperspectral imaging (HSI) data and the derived phenotypic measurements of the plants captured by the [Ag Alumni Seed Phenotyping Facility (AAPF)](https://ag.purdue.edu/aapf/).
+This document details the file system organization and navigation procedures for accessing both unprocessed hyperspectral imaging (HSI) data and the derived phenotypic measurements of the plants captured by the [Ag Alumni Seed Phenotyping Facility (AAPF)](https://ag.purdue.edu/aapf/). The data can be categorized into three main parts:
 
 - `Raw Scanned Data`: This folder structure houses individual scans (.hdr, .md5, .raw, .tiff) for each measurement.
 - `Interim Data Product`: This data contains data used for quality control procedures and images representing various vegetation indices.
 - `Masterfile (.xlsx)`: This file contains a compilation of spreadsheets and a guide document explaining the data contents.
 
+## Table of Contents
+
+### [File system structure](#file-system-structure)
+#### Raw Scanned Data
+#### Interim Data Product & Masterfile
+### How to Read Information in Header Summary (header_summary_plants.csv, header_summary_ref.csv)
+### Interpretation of Animated GIF Files for VNIR-SWIR Coregistration Quality Assessment
+### How to Read Information in Spreadsheet file (.xlsx, masterfile)
+
+___
 
 ### File system structure