and is represented by the
icon.Numera's Multiple Document Interface
Numera is a Multiple Document Interface (MDI) application. Let's explain that concept in terms that
most people are familiar with. Imagine a program that was a word processor, a spreadsheet and a
database all in one.
With that program you can have open, at the same time, for example, 2 word processor files, 3
spreadsheet files and 1 database file, and you could "switch" between them, and also exchange data.
The "multiple document types" in the preceding example are the word processor, the spreadsheet and
the database. You can have multiple "views" of each document type open at the same time, as described
in the example above.
Numera's document types are Expressions, Fractions, and the Function Grapher.
The Numera Expressions document is used to calculate mathematical expressions. Its file extension is ".nexr"
and is represented by the icon.
The Numera Fractions document is exclusively used to calculate with fractions. Its file extension is ".nfrc" and
is represented by the 
icon.
The Numera Function Grapher document is used to plot curves. Its file extension is ".nfgp" and is
represented by the 
icon.
The picture below shows an example of the 3 document types being open, each with one view, with the
Expressions document selected. All 3 are from our tutorials. The Sunrise Theme is shown.
