In the world of door furniture it's never very long before the security of a system is discussed, and it always seems as if there are as many solutions as there are ideas.
Insurance companies can dictate the manner in which the work is carried out as they often have fixed ideas on what is best, and offer appropriate discounts if their demands are met.
There are times however when security is required to keep out those with criminal aims.
There are other times where secure documents are kept, but you require a large amount of people to be let into the building or parts of the building.
In this case the typical lock and key system becomes very cumbersome, as it can be difficult to manage who does or does not have access to the key.
One system that has become quite a favourite is the digital door lock with handles.
This type of digital door lock has a turning handle, which operates the latch for the door; but a code must be entered before the handle can be turned.
The code for the door is a discrete arrangement of letters and numbers which can be pre-set into the digital door lock and handle.
The code arrangement is usually made from 2 vertical lines of keys.
On the left hand side are keys 1 to 5 inclusive and the letters X and Y.
On the right hand side are numbers 6 to 0 and the letters Z and C.
The code can usually be up to 6 digits in length and ideally should include at least one letter.
The C key is a 'clear' key, which should be used to ensure the code is not contaminated by previous insertions.
Note that any number or letter can only be used once and the code can be inserted in any order.
The code is then entered and the door opened.
If an error has been made the C key can be pressed and the code reinserted.
The code can then be given to all the people that need unsecured access to the room or building.
However, the digital door lock system has one or two faults.
Firstly the code can be given to an unauthorised person by any one of the code holders.
It is sensible to change the code on a regular basis to prevent unauthorised access, but this is very rarely carried out.
The second problem is that people can forget the code, particularly if they are elderly or new to such key code systems.
It is therefore sometimes useful to make the code not too long, or something which can be remembered.