The JIRA Info section in the System Info page under Administration is missing some information. Basically, it has all the fields in
atlassian-jira-enterprise-3.13-source/rpc-jira-plugin/src/java/com/atlassian/jira/rpc/soap/beans/RemoteServerInfo.java
but apparently none of the fields in
atlassian-jira-enterprise-3.13-source/rpc-jira-plugin/src/java/com/atlassian/jira/rpc/soap/beans/RemoteConfiguration.java

These are the missing fields:

   private boolean allowAttachments = false;
    private boolean allowUnassignedIssues = false;
    private boolean allowVoting = false;
    private boolean allowWatching = false;
    private boolean allowTimeTracking = false;
    private boolean allowSubTasks = false;
    private boolean allowIssueLinking = false;
    private boolean allowExternalUserManagment = false;
    private int timeTrackingHoursPerDay;
    private int timeTrackingDaysPerWeek;

This information is an important part of how a JIRA instance is configured.