Dates in Crunchbase are unlike typical Date in software development. In Crunchbase, components of the Date are often optional.
For example, when a user enters a died_on_date for a Person, the system requires only that the contributor enter a year.
In the screenshot below, the user is entering the Deceased date for Steve Jobs as 2011, omitting both month and day. Whereas this is valid input, the resulting Date stored in the Graph (and returned from the API) is "2011-01-01". Without more information, a developer cannot know that the month and day were not provided.
Here enters the TrustCode. TrustCodes indicate which portions of a Date can be "trusted". In other words, a TrustCode tells a developer which pieces of a Date were entered by a user and which were omitted.
Using the table below, the Deceased trust code for the Steve Jobs example would be 4, meaning that only the year (2011) could be trusted / was entered.
null or invalid date
day + month
year + day
year + month
year + day + month