Dictionary selection

Selecting the best dictionary to use and how to use it is worthy of serious consideration.
Some dictionaries are available as open source whilst others are bundled with tools. Some are fixed and others are flexible. Some come ready loaded with attribute values whilst others are completely blank.
Dictionary quality is important; too few attributes and items will be insufficiently described. If there are too many attributes, they will never be completed.
Dictionaries are like the story of Goldilocks and the three bears. You need to find one that is just right!
A good dictionary is concise and not too deep. You are attempting a balancing act of getting just enough information into your descriptions so items are well defined without excessive detail so that it takes hours to complete. Remember that having 14 attributes for a relay is all well and good but you will probably only have room in the short description for the noun modifier and 5 attributes.
Attribute order and priority is a factor when assessing dictionaries. Can attributes be re-ordered, amended, inserted and prioritised? Can attributes be marked as mandatory or preferred? Can attributes be marked as equivalent or alternates? Can attribute values be managed and controlled or specified within ranges?
Most material masters of around 50,000 lines will need about 1,800 noun modifier pairs to adequately describe all the items.
Most commercial dictionaries will have over 3,000 noun modifier pairs to choose from.
Each noun modifier pair has a set off attribute labels. Each label has a range set of allowable values and where appropriate a relevant unit of measure. Because an attribute can have more than one legitimate unit of measure it is essential that the values and units are held separately.
The number of attributes against each noun modifier pair needs to be looked at in context. Just because you could include colour as an attribute for every item in the material master does not mean that it is necessary or desirable.  

Example

An o-ring or toroidal seal has a selection of characteristics used to describe it succinctly. There are a number of additional attributes that could be captured. The question is do you need them? Can they be derived or sourced after the item has been identified? What is the essential information to be captured?

Some manufacturers supply items with both metric and imperial information. Whilst the dictionary must be designed to handle mulitple attribute units of measure, an overall guide is recommended. The generally accepted unit of measure should take preference. What is not good practice is making in-house conversions. Certain material can be metric, imperial or sometimes even mixed. For example, sheet material is often supplied in 8ftx4ft sheets with the thickness specified in mm.

Flexibility

When you start to catalogue data using structured templates, if you do not have a little bit of flexibility then you can quickly become frustrated with the rigidity. An acceptable compromise is to use the attribute called type. Normally this will be seen as the first available attribute.

Maintenance

Just as data quality can lapse over time, the same can be true for dictionary quality. Dictionaries need to be maintained, monitored and updated. Increasingly, best practice recognizes the necessity of creating a specialised role for dictionary governance. Maintaining a dictionary can be a time consuming activity, its often best to begin by concentrating on the high frequency templates. The top 20 templates will probably account for over 60% of the data volume. Control should be focussed on the allowable attribute values, this helps to maintain consistency and reduces the likelihood of duplicates being created. Duplicates should be avoided at all cost.