With the Construction tools, you can reference points in your drawing or measure distances from a set baseline.  

Column balloon

Column balloons serve as callouts for referencing the location of objects in the drawing, as in this example:

They have a functionality similar to that of the Incrementer tool, where each balloon you place automatically advances to the next number or letter.

To place a column balloon, follow these steps:

1. Under Construction tools on the Tools component tab, click the Column balloon component:
   
   
   
   
2. Move the cursor to the 2D drawing area. The quick properties box offer the following options:
   • Type: Select which pattern the increment should follow - numbers alternatively lowercase or uppercase letters.
   • Value: Override the automatic increment by specifying any value in this field.
   • Prefix: Set a unique text to precede the incremented number or letter.
   • Suffix: Set a unique text to follow the incremented number or letter.
   • Group: Add a custom group to enable showing hiding groups of column balloons in the Paper View (using a View Clip with the Column Balloon add-on).
     
     
3. Position the end of the column balloon line on the object that you want to reference and click once to attach the column balloon.

After placement, you can select a column balloon and move it, rotate it, or change its properties.

Baseline

Baselines are used together with baseline dimensions to get a distance from any point in the drawing to a shared baseline.

To place a baseline, follow these steps:

1. Under Construction tools on the Tools component tab, click the Baseline component:
   
   
   
   
2. Move the cursor to the 2D drawing area. You can specify an elevation in the quick properties box in this step.
3. Click once to set the starting point. The quick properties box now lets you control the baseline's coordinates, length and X / Y / Z angles.
4. Start moving the cursor in the desired direction and click to set the endpoint.
5. To place more baselines, repeat steps 3-4.
6. When finished, press the Esc key or move the cursor off the drawing area to release the baseline component.
7. The last baseline placed is selected at this point and can be edited through the quick properties:
   • Lock: Locks the position and all properties of the baseline (unlike the Lock option in the right-click menu that only locks the position).
   • Main Baseline: Check the box to make the selected baseline Main.
     Only one baseline in each direction is allowed to be the Main Baseline.
   • Name: Lets you pick a custom name for the baseline.

Baseline dimension

A baseline dimension shows the distance from the dimension benchmark to a baseline. Let's look at a couple of illustrations to see how it works.

During placement

When you have a baseline dimension attached to the cursor in the 2D view, it could look something like this:

The blue frame marks the dimension line which is the benchmark for measuring the distance. Since the To Baseline option is set to Auto in the quick properties box it is referring to baseline C, which is the baseline closest to the benchmark.

After placement

Once you click the baseline dimension in place, this is what you will see:

The green line marks the distance that the baseline dimension is measuring, i.e. from the benchmark to baseline C.

To place a baseline dimension, follow these steps:

1. Under Construction tools on the Tools component tab, click the Baseline dimension component:
   
   
   
   
2. Move the cursor to the 2D drawing area. The quick properties box offer the following options:
   • Ref. Texts: Select Manual to allow custom referencing texts, or select Standard to only allow standard, predefined referencing texts.
   • Text / Auto Text: If Ref. Texts is set to Manual, this field lets you specify a custom referencing text for the dimension. If Ref. Texts is set to Standard, you pick a predefined text from the dropdown menu.
   • Replace: Only available if TYP(#) was selected in the dropdown above. The # symbol is replaced with the text entered in the Replace field.
   • To Baseline: Shows which baselines the current dimension can refer to. The Auto option will suggest a baseline based on the benchmark position, or you can specifically select which baseline the dimension should refer to.
   • Direction: Rotates the dimension 90° at a time.
   • Associative: Keeping this checkbox selected means that the dimension is associative, i.e. that it moves together with the object it is measuring from, for example a column.
     
     
3. Click once to set the starting point.
4. Start moving the cursor in the desired direction, or use the Length and Depth fields in the quick properties, to create your dimension.
5. Click to set the endpoint.
6. To place more baseline dimensions, repeat steps 3-5.
7. When finished, press the Esc key or move the cursor off the drawing area to release the baseline dimension component.
8. The last baseline dimension placed is selected at this point and can be edited through the quick properties:
   • Show Name: Enables / disables showing of the dimension name, as specified in the Text field.
   • Text Display: Choose the desired way to display the text with your dimension: Dimensions only, Text only, Text & dimensions, Text & dimensions on separate lines, or Text & dimensions on multiple lines.
   • Text: Type the text you would like to show with or in the place of your dimension text.
   • Line length: Increase or decrease the line length of the dimension. You can also do this with the stretch node of the top line of the dimension.
   • Text rotated: Select this box to toggle between horizontal and vertical text.
   • Text Style: Use the dropdown to select a predefined style or click Edit to customize Font, Font height, Font color, and more.
   • Dimension Style: Use the dropdown to select a predefined style or click Edit to customize Distance unit, Arrow head type, and more.