Working with Attributes
An Attribute is Similar in Ways to a Cell in a Spreadsheet
Each object in your document starts out with nine default attributes. These nine attributes are called elements, since they correspond to faces and dimensions, which are elements of the object.
Axes Positioning Attributes Dimensioning Attributes X Left Right Width Y Front Back Depth Z Bottom Top Height
Every attribute has a name, a value and an expression. You can think of an object as a spreadsheet, and an attribute as a cell in that spreadsheet, and the attribute's expression as the formula in that cell, and the value as what's visible in the cell. The value is computed from the expression. Expressions can, and often do, refer to other attributes. The value is used by Design Intuition to draw the object in the document views. The expression is used to relate an object to its containing group, within the object hierarchy.
An object's element attributes already have their own expressions, created for them when the object was created. You can, however, alter any of their expressions for any purpose you can imagine.
Furthermore, as will be explained in more detail on the next web page, each row in the table above is called an axial triad.
Okay, that's a lot of facts all at once. What it boils down to is this: attributes play a key role in the user interface and, by being editable in all the above ways, give you very powerful and precise control over your designs. And, of course, that's only the beginning of the story...
Now For Something Completely Unexpected
The value of an attribute can be set by the user interface or directly by you. Quite counterintuitively, however, Design Intuition then alters the expression so that when re-evaluated, the expression computes exactly to the newly set value. This is done for you, thousands of times a second, when you move or resize an object. This is a key feature of Design Intuition. This saves you from ever having to re-edit your expressions, once you get your expressions right.
I like to call this reverse parsing, because it sounds mysterious and techy; but technically it is more like something taught in eighth or ninth grade: solving for an independent variable. But that's not quite it either. The name has stuck, though.
You can turn this feature off in any attribute by checking the locking the Value (by clicking on the padlock to close it). Doing so prevents the attribute from being changed by either graphical or numerical editing.
Authored Attributes
You can add your own attributes to any object in your document. You typically add them to the outermost group so that all your objects can share them. The spreadsheet metaphor works here as well: You can think of the outermost group as the spreadsheet that all other objects can refer to. Or, if you like, think of the outermost group as the top of the family tree, and all of the objects within the outermost group as its descendants.
One recommendation: for sanity's sake, you probably will want to use unique names when creating attributes.
What is Show Units?
You can control the way a value is displayed in the document and object inspectors by checking or not checking the Show Units checkbox. The only time you might not want to check this is when the attribute is not being used as a geometric (positional or dimensional) value. The only examples I could think of as I designed this program are ratios, multipliers and divisors; perhaps you will think of other uses.
