Clarify units and g-force for accelerometer

neon/data-collection/data-format/index.md

@@ -1,7 +1,7 @@
 # Recording Format
 The page describes the data format when downloading Neon recordings from Pupil Cloud in the "Timeseries Data" and "Timeseries Data + Scene Video" formats. In this format the Data from the Neon Companion is augmented by adding gaze and eye state estimates whenever they had not been computed in realtime. Futhermore fixations and blink data as well as some IMU transformations are computed.
 
 When downloading Native Recording Data from cloud or direclty [extracting it via usb from the companion device](/data-collection/transfer-recordings-via-usb/), use the [pl-neon-recording](https://github.com/pupil-labs/pl-neon-recording) python library to read and access the data. This data format will contain all video data as well as all data that had been computed in realtime on the companion device.
 
 
 ## Recording Folders
@@ -19,7 +19,7 @@
 | **android_device_model**  | Model name of the Companion device.     |
 | **android_device_name**   | Device name of the Companion device.     |
 | **app_version**           | Version of the Neon Companion app used to make the recording. |
 | **calib_version**         | Version of the offset correction used by the Neon Companion app. |
 | **data_format_version**   | Version of the data format used by the Neon Companion app.     |
 | **duration**              | Duration of the recording in nanoseconds|
 | **firmware_version**      | Version numbers of the firmware and FPGA. |
@@ -47,7 +47,7 @@
 | Field | Description | 
 | -------- | -------- | 
 | **camera_matrix** | The camera matrix of the scene camera.     |
 | **dist_coefs** | The distortion coefficients of the scene camera. The order of the values is `(k1, k2, p1, p2, k3, k4, k5, k6)` following [OpenCV's distortion model](https://docs.opencv.org/4.x/d9/d0c/group__calib3d.html#ga3207604e4b1a1758aa66acb6ed5aa65d). |
 | **serial_number** | Serial number of Neon module used for the recording. This number is encoded in the QR code on the back of the Neon module.      |
 | **version** | The version of the intrinsics data format.     |
 
@@ -110,16 +110,16 @@
 | **azimuth [deg]** | The [azimuth](https://en.wikipedia.org/wiki/Horizontal_coordinate_system) of the gaze ray corresponding to the fixation location in relation to the scene camera in degrees.     |
 | **elevation [deg]** | The [elevation](https://en.wikipedia.org/wiki/Horizontal_coordinate_system) of the gaze ray corresponding to the fixation location in relation to the scene camera in degrees.     |
 
 ## saccades.csv
 This file contains [saccades](/data-collection/data-streams/#fixations-saccades) detected by the fixation detector.
 
 
 | Field | Description | 
 | -------- | -------- | 
 | **section id** | Unique identifier of the corresponding section.     |
 | **recording id** | Unique identifier of the recording this sample belongs to.     |
 | **saccade id** | Identifier of the saccade. The counter starts at the beginning of the recording.     |
 | **start timestamp [ns]** | UTC timestamp in nanoseconds of the start of the saccade.     |
 | **end timestamp [ns]** | UTC timestamp in nanoseconds of the end of the saccade.     |
 | **duration [ms]** | Duration of the saccade in milliseconds.     |
 | **amplitude [px]** | Float value representing the amplitude of the saccade in world camera pixel coordinates. |
@@ -165,7 +165,7 @@
 | **recording id** | Unique identifier of the recording this sample belongs to.     |
 | **timestamp [ns]** | UTC timestamp in nanoseconds of the sample.    |
 | **gyro x [deg/s]**<br />**gyro y [deg/s]**<br />**gyro z [deg/s]** | Rotation speed around x, y or z-axis respectively in degrees/s.    |
-| **acceleration&nbsp;x&nbsp;[G]**<br />**acceleration&nbsp;y&nbsp;[G]**<br />**acceleration z [G]** | Translational acceleration along the x, y or z-axis respectively in G. Note `1 G = 9.80665 m/s^2`.|
+| **acceleration&nbsp;x&nbsp;[g]**<br />**acceleration&nbsp;y&nbsp;[g]**<br />**acceleration z [g]** | Translational acceleration (in terms of [g-force](https://en.m.wikipedia.org/wiki/G-force)) along the x, y or z-axis respectively. Note `1 g = 9.80665 m/s^2`.|
 | **roll [deg]** | Drift-free estimate of the roll (head tilt from side to side) in degrees. The output range is -180 to +180 degrees. Added in version 2 of this enrichment.    |
 | **pitch [deg]** | Drift-free estimate of the pitch (head tilt from front to back) in degrees. The output range is -90 to +90 degrees. Added in version 2 of this enrichment. |
 | **yaw [deg]** | Drift-free estimate of the yaw (horizontal head rotation) in degrees. The output range is -180 to +180 degrees. Added in version 2 of this enrichment. |