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[protege-discussion] slots

Simon White swhite at
Mon Nov 17 11:43:51 PST 2008

Hi Jason,


Yes, as Csongor mentioned I have developed a slot widget plugin for Protege
Frames that provides support for engineering units. I also have a slot
plugin to support Dates. You create a  slot of type String and assign the
Date slot widget to it. This plugin ensures that the date is stored in a
consistent format (e.g. for machine reading) and allows you to pick a date
from a drop-down date picker component.


For slots that need engineering units support, you use a different
meta-class (a subclass of :STANDARD-SLOT) and this allows you to choose a
new slot widget in forms so that the associated units are displayed.

The plugin supports conversion between units, setting default units (for
example SI units) and remembering your chosen units.

You can convert only between units of the same 'Dimension' (a.k.a
'Quantity'). For example you can convert between millimetres and inches
because they are both lengths, but not between millimetres and kilograms.
When you create a slot, you specify its dimension, so that only meaningful
conversions are offered.


There is also a more advanced concept called a unit group that allows you to
group together units from different dimensions. For example, you sometimes
might want to specify an amount of something either by weight or by volume.
Lastly, the approach is extensible - I have provided a units framework, but
you can populate it with your own units if I have not provided the ones you


Simon White    


PS. The widgets have not been tested with the latest versions of Protege,
but I can check compatibility and fix any bugs if there is sufficient


From: protege-discussion-bounces at
[mailto:protege-discussion-bounces at] On Behalf Of Csongor
Sent: 13 November 2008 01:34
To: User support for Core Protege and the Protege-Frames editor
Subject: Re: [protege-discussion] slots


Hi Jason,

There is some good news for you. See below.

Jason Sachs wrote: 

is there a way to restrict a slot of type String to a date/time value? (I
don't see a Date or Time type)

Yes there is, but only for OWL ontologies. I suppose you are using Protege
version 3.X.
First you have to make sure that Protege uses the special datatypes that you
want. Go to the menu
OWL-> Preferences select the Datatypes tab and make sure that you have
selected the types that you need: xsd:date, xsd:dateTime, xsd: time etc.
After this is done, whenever you create a new Datatype property, you will
have the previously selected types available as possible Range values.
For any functional datatype property for which you have specified as its
range one of the date/time datatypes, you will be able to present that
property with the OWLDateWidget, at any class that is part of the domain of
that property. Please be aware that the OWLDateWidget is not applicable to
non-functional properties.

also is there any way to associate engineering units with a Float value?
(like if I want a length in millimeters) I don't really need a user to
change units, but it is disconcerting in the Instance Editor if they will
type in a floating-point value without any indication of whether it's
supposed to be mm or inches or feet or whatever.

There is a "Units" plug-in developed by Catalysoft [1] that may do what you
want. This plug-in was presented by the company's representative, Simon
White, in the poster&demo session of the Protege conference from 2007. You
may want to read the abstract of the demo [2] available on the Protege



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