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To create a conditional dimension you click on 
a conditional dimension
Give it a name
Select visibility
Choose category
Select conditions
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Step 1.
First, You have to give a name to your conditional dimension. Give it a clear name so you can identify it easily when creating a report.
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Ideally, you would chose Primary for those dimensions that are the most important and Secondary for those that will appear below the line.
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Step 3.
Choose the category based on the dimensions used for the conditional dimension. The categories you can choose from are the following: Affiliation, Analytics, Custom, Direct, Display, Email, Retargeting, SEA, Shopping, Social Ads, Social organic, Spot TV, Video
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Finally, all of your campaigns have an objective, so nothing should be left blank, but in case that happens you can put “N/A” for not available in the “else the dimension value will be” field.
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Then click on the Create/Modify button and you can already use your newly created dimensions in all your reports as you can see here:
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