Sometimes you do not want a record or a child record to be added if the incoming data has a specific value. At the time of writing this there is no explicit setting for this (although this is planned). However there is a workaround for a number of child records.
Almost all area mappings require one or two specific fields to have a value for them to actually import. For example if you leave the attribute category blank it will not import even if there is a description, a date or a comment. The same goes for phones when the phone type field is blank. In these cases if the attribute category is set using a transformation then it can be set to blank if an incoming value should prevent the attribute from being created.
For example, We only want to add a "T-Shirt size" attribute category if the incoming data has a field value of "Child" we would map the incoming Child/Adult field to our attribute category. In the transformations we would create a new transformation that says: If the incoming value is "Child" transform the value to "T-Shirt size". Then can then do the same for "Adult" except set the transformation to blank. Alternatively tick the catch all tick box and leave the transformation blank. This means that any other values will be transformed to blank.
The process will then only add the attribute for children.