每个模版有不同的必填字段与选填字段https://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/subscribe-message.htmlhttps://developers.weixin.qq.com/miniprogram/dev/OpenApiDoc/data-analysis/others/getVisitPage.htmlhttps://developers.weixin.qq.com/miniprogram/dev/OpenApiDoc/data-analysis/visit-retain/getWeeklyRetain.html
什么使用场景，怎么理解？