diff --git a/OpenAPI/openapi.yml b/OpenAPI/openapi.yml
index 97888bcc8e77f3839aea60054e97139a97c5c238..bbe7c6af757ca1601ecbc495135633189b0fd5a2 100644
--- a/OpenAPI/openapi.yml
+++ b/OpenAPI/openapi.yml
@@ -5,13 +5,99 @@ info:
   version: '0.1'
   
   description: >
-    ## Introduction
-  
-  contact:
-    name: Benjamin Montavon
-    email: b.montavon@wzl-mq.rwth-aachen.de
+    ## Introduction  
+
+    This interactive document describes how to interact with the unified interface for *Large-Scale Metrology* devices which was
+    developed during the LaVA project. The interface itself is based on the *Sensor Interfacing Language (SOIL)* which in turns was
+    developed in the Cluster of Excellence *Internet of Production*.  
+
+
+    The chosen approach decouples the unified modeling of different Large-Scale Metrology systems, the general information model for sensor
+    systems, and the communication using standardized protocols. These three topics will be briefly covered here, for more conceptual details, the reader
+    is kindly asked to refer to [https://doi.org/10.18154/RWTH-2021-10238](https://doi.org/10.18154/RWTH-2021-10238).
+
+    ## Sensor Interfacing Language (SOIL)  
+
+
+    To further reduce complexity and provide concise representations, a division of resources into Objects (OBJ), Functions
+    (FUN), Variables (VAR) and Parameters (PAR) only offering specific subsets is proposed:  
+      * **Objects** provide an object-oriented data view and in combination with structured
+      identifiers are the only resources allowed to posses subordinate child items.
+      * **Variables** encapsulate access to data with physical origin, e.g. measurements, which
+        are naturally read-only. 
+      * **Parameters** separately encode read and potential
+        write access to primitive data fields. 
+      * **Functions** are resources that are callable with a set of argument and return values, leading to a function invocation on the resource.
+
+    The overall organization of SOIL is hierarchial, using locally unique identifiers (uuid) which can be concatenated to a fully
+    qualified identifier, which e.g. serves as URL. Only Objects are allowed to have child items. Each resource types comes
+    with a defined set of metadata to ensure high data quality, especially for long-term objectives. The metadata fields are described in the
+    schema section of this document.
     
 
+    ## Modeling of Large-Scale Metrology Systems  
+
+    For the unified modeling of Large-Sale Metrology systems, a functional view from an application's perspective
+    was adopted over a physical view exactly representing the embodiement of the system. Hence, a Large-Scale Metrology System is modeled as:
+      * A set of **base stations**, which are fixed and have an enabling role. In case of a centralized system, there
+        is exactly one base station. Examples are a laser tracker head, indoor GPS transmitters, OPTIMUM Heads or distributed cameras.
+      A fixed-type kinematic, as e.g. for CMMs, is also interpreted as base station.
+      * A set of **mobile entities**, which corresponds to the targets whose positions are measured. In the information model,
+        the measurement of the current position is always retrieved through the corresponding mobile entity, even if 
+      it is effectively measured at the base or through multilateration or multiangulation. Examples are SMRs, n=2 spheres
+      indoor GPS PCEs or photogrammetric targets.
+
+    This approach organizes the entire information model under four elements:
+      * **Root**  The root object is the entry point for the Large-Scale Metrology as general device, accomodating elements
+        which are rather general (e.g. Startup and Shutdown)
+      * **LSM** The Large-Sale Metrology (LSM) objects represents the model briefly described above. It can be integrated
+        into more complex models and therefore is a node on its own.
+      * **Entity** For each mobile entity, an own object containing the relevant functions, parameters and variables is present.
+        Each entity has an *uuid* to address it.
+      * **Base** For each base station, an own object containing the relevant functions, parameters and variables is present.
+        Each entity has an *uuid* to address it.
+
+    These elements are used as tags to organize the description below.
+    
+    ## REST and MQTT Access  
+
+    SOIL is protocol-agnostic by definition, i.e. it may be mapped to HTTP/REST, MQTT, OPC UA, grpc.io and many more.
+    This document describes the mapping to HTTP/REST and MQTT using JSON for serialization. The HTTP Verbs are translated to
+    READ, UPDATE, CREATE, REMOVE and INVOKE to act on the resources. The elements are addressed through their FQID as URL or MQTT topic, 
+    while the FQIDs may be prepended with global prefixes. The significance of the individual methods as described under the **Any** tag below
+    and not repeated here. For using MQTT, the device's implementation must connect to broker provided outside it scope to which the user can subscribe.
+    The serialization is expected to be identical both via HTTP/REST and MQTT and to follow the schemas provided in this document. The minimum requirement for
+    an MQTT-enabled device is to publish the updates to its Variables, while it is recommended to also publish Parameter updates.
+
+    ## Testing
+
+    This OpenAPI scheme can be used as a client to interact with the HTTP/REST part of a Large-Scale Metrology system's interface.
+    The reader is kindly referred to open source tools available for this purpose. 
+
+    Currently, the provision of virtual Large-Scale Metrology device at [https://iot.wzl-mq.rwth-aachen.de/public/SOIL/devices/LSM/](https://iot.wzl-mq.rwth-aachen.de/public/SOIL/devices/LSM/)
+    is planned. As an alternative, testing with a local implementation (e.g. at [http://localhost:8000/](http://localhost:8000/)) is possible.
+
+    ### Acknowledgements
+
+    The authors acknowledge funding from the LaVA project (Large Volume Applications, contract 17IND03 of the
+    European Metrology Programme for Innovation and Research EMPIR). The EMPIR initiative is co-funded by
+    the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.  
+    
+
+    The authors would like to thank the German Research Foundation DFG for the kind support within the Cluster
+    of Excellence Internet of Production - Project-ID: 390621612.
+
+    ### Contact  
+
+    Dr.-Ing. Benjamin Montavon  
+
+    [b.montavon@wzl-mq.rwth-aachen.de](mailto:b.montavon@wzl-mq.rwth-aachen.de)  
+
+
+    Matthias Bodenbenner, M.Sc.  
+
+    [m.bodenbenner@wzl-mq.rwth-aachen.de](mailto:m.bodenbenner@wzl-mq.rwth-aachen.de)
+  
 servers:
   - url: http://localhost:8000/
   - url: https://iot.wzl-mq.rwth-aachen.de/public/SOIL/devices/LSM/