Understanding filters

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Introduction

This is an image of the filter boxes

Filters are lists of words that you specify in order to limit the kind of alerts that a user will receive. Filter words are generally compared to the title of an alert, and also to the list of units dispatched (if given). If an alert has the title GENERAL ALERT, we will also search against the "place" name.

Filters are found under the Devices tab in your Active911 account. Click on a device to edit its associated filters.

Additionally, filters can be modified directly by the user of a given device.

In detail

To understand how filters work, you will need to consider what shift settings you have set for this device. This is because there are two filters, one for when this device is off duty, and one for when it is on duty.

The words "duty" and "shift" are used interchangeably here. The default setting for all devices is to be on duty at all times; if you have not changed this then you can safely ignore the "off duty" filter.

Filters are simply lists of words, separated by commas, that must match in order for a page to be sent to your device.

When a device is on duty, the on duty filter will limit the type of messages received. The default for on duty, when no filters are given, is to allow all messages. This means that a device will receive all alerts if it is on duty and you do not specify a filter. If you do type one or more filter words, at least one of the words must match .

Example on duty filters

  • fire, burn will match "HOUSE FIRE", "BURN COMPLAINT", AND "FIREHOUSE DRILL" but not "MVC INJURY" or "CARDIAC ARREST"
  • E231, E232 will match any call that lists E231 or E232 in the list of dispatched units

When a device is off duty, the off duty filter will be used. The on duty and off duty filters work the same way, but with one important difference: the on duty filter allows all alerts by default, but the off duty filter will block all alerts by default. This means that a blank of duty filter will not allow anything through while off duty.

Advanced filters: regular expressions

Filters can also support advanced filtering using a filter language called regular expressions. Here are some common regular expressions (more details on this subject are available elsewhere on the internet):

. (a period)
means "any single letter". For example, "E99." would match E991, E992, E993, and so on.
^
means "beginning of line". ^FIRE would match FIRE AT MILL but not HOUSE FIRE
$
means "end of line".
\w
means "any letter or number".
\b
means "word boundary". HIGH\b matches TOO HIGH but not HIGHER.

Much more information on regular expressions can be found online. One tutorial can be found here.

Examples

I want to receive all alerts while on duty, but only MCI and MAJOR calls while off duty.
  • On duty filter: leave blank
  • Off duty filter:MCI, MAJOR
I work on team A11, and I am on call for team B12. I want all alerts for B12, day or night, but only A11 when on duty.
  • On duty filter: A11, B12
  • Off duty filter: B12
My alerts look like this--"TC (traffic crash)", "UM (unknown medical)", "WATCH (fire watch)" etc. I want to receive TC and TC0 through TC1 calls, but nothing else. I want no alerts when off duty.
  • This one is tricky. If we just type "TC", we will get both TC and WATCH because WATCH has the letters TC in it. We will need regular expressions. On duty filter: ^TC, ^TC0, ^TC1
  • Off duty filter: Leave blank
I want everything BUT calls that start with the word GENERAL.
  • ^((?!GENERAL).)*$