Technical Details


This eGuide uses hand coded HTML5 markup and CSS3 layout.

A small amount of javascript (ECMA-262 v3 1999) is used :-

  1. to initiate and run the service worker,
  2. to permit smooth scrolling between links and anchors on the same page,
  3. to add a jscript javascript library.

The eGuide will still function if javascript is disabled apart from loading the guide in the off-line cache and updating.

If CSS is disabled the text will display correctly and navigation remains enabled.


Use is made of HTML5 semantics as well as additional aria roles and access keys in order to enable assistive access for keyboard users and those with impaired vision. All modern browsers contain additional accessibility features which compliment those incorporated in this eGuide.


W3C Standards

The guide complies wherever possible with W3C-AAA standards.


Compliance Testing

This guide has been tested for compliance with the above standards. Most symbols used within the guide are web-font icons not images - automated colour tests give false contrast errors on the web fonts despite the colours used complying with, and in most cases exceeding, the standard.



The eGuide is responsive and will adjust layout to suit a wide variety of screens from smart-phones to tablets and desktops.


Service Worker

This eGuide uses a Service Worker script which sits between the web page and the network, providing cached versions of the site when no network connectivity is available. The service worker runs in the background making the decision to serve network or cached content based on availability. The older form of browser caching, AppCache is no longer supported.

The service worker will install and subsequently update the eGuide in the background without any user intervention. Updates will become active the next time the guide is opened after the update has been uploaded and will replace the older stored data held in the cache.

The eGuide, despite consisting of over 1400 files, only takes up around 12mB in storage space. Once the service worker has installed all subsequent browsing through the guide uses the stored cache data (except where an external link is selected) and so will have no impact on data usage except when updating.

The guide will run perfectly well without service worker being installed providing a network connection to the internet is maintained.

Service workers support is available in the latest version of the following browsers - Google Chrome, Chrome for Android, Mozilla Firefox, Samsung Internet, Opera, Microsoft Edge, Apple Safari (OSX and iOS from version 11.3 - fully implemented with auto updating from iOS 12.2), UC Browser for Android, Android WebView.

See Installation and Updates page for further details.

It is expected more mobile browsers will soon also be supporting the technology - see Is service worker ready?



Our standard licence is based on usage by an individual on as many devices as is required. In other words the licence permits a person to access the eGuide on a desktop as well as a mobile device or devices. It does not apply to the number of simultaneous users but the total number of individual users permitted access to the guide. This also means that a force or company can purchase a licence for an individual for use on his or her own device as well as or instead of the force or company's resources.


Minimum Requirements

This eGuide will work on older versions of browsers (IE v8 upwards) however in order to get the best out of the guide we recommend updating to one which fully supports Service Workers and HTML5.