bookmark-version-controlbookmark-version-control is a variable defined in `
bookmark.el'. Its value is
nospecialDocumentation: Whether or not to make numbered backups of the bookmark file. It can have four values: t, nil, `never', or `nospecial'. The first three have the same meaning that they do for the variable `version-control'; the value `nospecial' (the default) means just use the value of `version-control'. You can customize this variable.