Fact sets are collections of fact types - or, more precisely, 'fact definitions'. Fact sets can be system level fact sets (meaning that they are not stored with the rest of your project data and are available for use with all projects on your PC), or they can be project level - which means that they are stored with your project data, and are only available for use with that particular project.
To work with fact types and fact sets, you need to access the Fact Types Dialog which you can do by clicking 'Fact Types' on the Tools menu. It shows the list of types of events and attributes (that is, 'facts') that are available to you to add to Individual and/or Family records.
Fact definitions include the fact name, type, label and much more, including a sentence template (for generating sentences in narrative reports, relating to this fact), and also definitions of witnesses for the given fact, and their roles, and sentence templates for witnesses. See Fact Definition Dialog for more details.
Custom fact sets can be imported and exported. See Creating and Deleting Fact Sets, and Importing and Exporting Fact Sets.
The Fact Types Dialog shows installed events and attributes. It will only show hidden ones if the ‘Show Hidden’ box is ticked. When hidden events and attributes are included, the list also has additional columns. Click on any column heading to sort the list by that column (or press ALT and click to reverse the sort). The columns are:
| Event/ Attribute | Each event or attribute has both a name and a label. Normally these are the same. The name never changes, but you can modify the label if you wish (see Properties). The label is normally used to identify the event or attribute in dialogs throughout the program. | 
|---|---|
| Label* | This is actually the same column. It is renamed to ‘label’ if you click on ‘Show Hidden’ to make it clear that it is the label that is being displayed in this column. | 
| Name* | As stated, this is usually the same as the label, but doesn’t have to be. You can change the label but you can’t change the name of an event or attribute. | 
| Type | Values here are event or attribute. | 
| Time Frame* | The possible values here are: 
 Time frame values are used for checking dates (e.g. to give warning if a burial death is before death date), for helping with ordering dates, and for determining whether or not age information should be displayed in the Facts tab of the Property Box. | 
| Fact Set | Shows the fact set that the event or attribute belongs to. Project level fact sets (see above) have the word "(project)" as a suffix, after their name. The ‘Standard’ fact set (which is a system level fact set) is the only one that comes pre-installed with the program. But you can create your own, or import other fact sets that others have defined. If an event or attribute has <none> as the fact set (you will only see this if you have ticked ‘Show Hidden’) this means that it is undefined - that is, it exists in the family tree file that you currently have open, but you do not have a definition for it. If you select it and click on the button, you will be told that is undefined, and given the opportunity to create a new definition for it. If, for example, you want to specify a sentence template for this type of fact (to generate an appropriate sentence in narrative reports say) you must create a definition for it. Fact sets are ranked in order of priority (see the discussion of the 'Visible' field below for why this is necessary). If you wish to view fact sets’ ranking, tick the ‘Show Set Rankings’ box. To change fact set rankings, click on the button. | 
| Visible* | The possible values here are: 
 A tick just means that the fact is not hidden. <hidden> means that you have chosen to hide it (typically you will want to hide any facts that you never use). <undefined> means that the fact is undefined (see previous discussion of the Fact Set column). The <eclipsed> value only arises if you have more than one fact with the same name, and neither of them is marked as ‘hidden’. This can happen. No two facts can share the same name within any given fact set. But there is no limit to the number of fact sets you can create or import, and it can happen that facts in different fact sets can have the same name. If you have 2 or more facts with the same name, and not marked as ‘hidden’, Family Historian will use the rankings of the fact sets to determine which to use (the only reason that fact sets are ranked is to handle this situation). In this case, the lower-ranked fact is ignored and will not appear in lists unless ‘Show Hidden’ is checked. Lower-ranked facts which have been ignored for this reason are said to be ‘eclipsed’. If you wish to enable an eclipsed fact you can do either by changing the rankings of its fact set to move it above the fact sets of the facts that are eclipsing it; or by hiding or deleting the eclipsing facts. | 
| Status* | The possible values here are: 
 A tick just means that the fact definition for this fact is enabled. Just because a fact is hidden does not mean that the fact definition associated with it is disabled and. will not be used. You may have hidden the ‘National or Tribal Origin’ attribute, for example, because you never use it. But suppose one day you open a GEDCOM file that contains such an attribute, and you decide to print a narrative report. Family Historian will use its fact definition for ‘National or Tribal Origin’ to determine how to generate a sentence for that attribute. However, if a fact is eclipsed (see discussion of the Visible field above) its fact definition will not be used, so the value here will be ‘<disabled>’. | 
* Only available when "Show Hidden" is selected.
| Fact Set | If you have multiple fact sets, you can view the facts for any one of them, only, by by selecting it from the dropdown list. Or choose <All> to view facts in all fact sets. | 
|---|---|
| Filter | Use this field to choose a particular subset of facts that you wish to view. | 
| Add | This button is only available when you access the dialog by clicking on the button on the toolbar in the Facts tab of the Property Box. Inserts the currently selected events or attributes into the current record. If 'Close Dialog after Adding' is ticked, the dialog will close afterwards. Tip: You don’t have to add just one fact at a time. You can select as many as you like (e.g. by pressing the Ctrl key while clicking on a fact to select it) and add them all in one go. Even just unticking and adding them one-at-a-time will speed things up if you have several to add, as you won’t have to keep re-opening the dialog box. | 
| More >> (<< Less) | This button is only available when you access the dialog by
              clicking on the  button on
              the toolbar in the Facts tab of the Property Box. If pressed it toggles between showing additional buttons down the right-hand side of the dialog box. | 
| New | Create a new fact definition. | 
| Edit | Edit a fact definition in the Fact Definition Dialog. | 
| Delete | Delete an existing fact definition. You cannot delete fact definitions in the Standard fact set. | 
| Fact Sets… | Displays Fact
                Sets Dialog which gives a list of fact sets currently in
              use, and their rankings. You can re-order them, clone them, delete
              them (custom fact sets only), or reset the standard fact
              set. The ‘Standard’ fact set can have any ranking like any other fact set. | 
| Show | This button will always be greyed unless ‘Show Hidden’ is checked. It will remove the ‘hidden’ status from all selected facts. | 
| Hide | Sets all selected facts to ‘Hidden’. Use this button to hide any
              events or attributes that you never use, so that they do not
              unnecessarily clutter lists. If you hide an event or attribute
              this only means that that fact type will not appear in most lists
              of fact types. It won’t result in any data in your records being
              hidden. Nor will any data in your records be changed in any way.
              You may never use a given event type, but if someone sends you a
              GEDCOM file containing an event of that event, it will still
              appear in your records as normal - even if you have hidden the
              corresponding event type from your lists. Hiding events and attributes you never use is just a convenient way of making lists more manageable. And you can always ‘unhide’ the same items in the future if you wish to. | 
| Show Hidden | If checked, hidden facts are displayed in the list as well as
              visible ones. Items can be hidden either because they are
              explicitly marked as ‘Hidden’ (you selected them and clicked on
              the  button); or because they are
              <undefined> or <eclipsed> (see above). Tip: When you click on the 'Show Hidden' tick box, Family Historian automatically adjusts columns to fit nicely into the list at its current size. So if you resize the dialog box you can force it to re-layout the columns for you, by clicking twice on this box. | 
| Show Set Rankings | Each fact set is ranked, starting from 1. You can change fact set rankings by clicking on the button. To view fact set rankings in the Fact Set column, tick this box. |