What does the searchable field safetyreportid mean in openFDA drug adverse event api

Question

In the openFDA website(https://open.fda.gov/apis/drug/event/searchable-fields), it said safetyreportid is "The 8-digit Safety Report ID number, also known as the case report number or case ID. The first 7 digits (before the hyphen) identify an individual report and the last digit (after the hyphen) is a checksum. This field can be used to identify or find a specific adverse event report." Sorry I was confused with some points of the definition.

1. What does checksum mean? Is that the version number?
2. I saw some case IDs with a hyphen (like '4322505-4') but some don't (like '10003310'), is it just because of the different format?

Answer 1

Each unique submission of a case received is given a version number (for example, Case# 1234567, Version 1). The first version received (formerly called Initial) will be version 1; the second version received (formerly called Follow-up 1) will be version 2, and so on. The latest version of a case represents the most current information about a particular case.