diff --git a/README.md b/README.md
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+++ b/README.md
@@ -89,6 +89,38 @@ relative_humidity:
 
 ```
 
+# How to Extend DIMA’s File Reading Capabilities for New Instruments
+
+We now explain how to extend DIMA's file-reading capabilities by adding support for a new instrument. The process involves adding instrument-specific files and registering the new instrument's file reader.
+
+## 1. Create Instrument Files
+You need to add two files for the new instrument:
+
+- A **YAML file** that contains the instrument-specific description terms. 
+  - **Location**: `instruments/dictionaries/`
+  
+- A **Python file** that reads the instrument's data files (e.g., JSON files).
+  - **Location**: `instruments/readers/`
+
+**Example:**
+- **YAML file**: `ACSM_TOFWARE_flags.yaml`
+- **Python file**: `flag_reader.py` (reads `flag.json` files from the new instrument).
+
+## 2. Register the New Instrument Reader
+To enable DIMA to recognize the new instrument's file reader, update the **filereader registry**:
+
+1. Open the file: `instruments/readers/filereader_registry.py`.
+2. Add an entry to register the new instrument's reader.
+
+**Example:**
+```python
+# Import the new reader
+from instruments.readers.flag_reader import read_jsonflag_as_dict
+# Register the new instrument in the registry
+file_extensions.append('.json') 
+file_readers.update({'ACSM_TOFWARE_flags_json' : lambda x: read_jsonflag_as_dict(x)})
+```
+
 ## -------------------
 ## Getting started
 
@@ -96,9 +128,6 @@ To make it easy for you to get started with GitLab, here's a list of recommended
 
 Already a pro? Just edit this README.md and make it your own. Want to make it easy? [Use the template at the bottom](#editing-this-readme)!
 
-## TODO
-* Talk to Thorsten about rga txt files. Example folder contains incosistent rga txt files, there is no unique column separator (, or )
-
 ## Add your files
 
 - [ ] [Create](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#create-a-file) or [upload](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#upload-a-file) files
diff --git a/TODO.md b/TODO.md
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@@ -0,0 +1,3 @@
+## TODO
+* Improve file reader for rga txt files (Talk to Thorsten). Example folder contains incosistent rga txt files, there is no unique column separator (, or ).
+* Improve documentation of file reader extensions. Specify PY file reader template with expect input and output and file naming convention.