https://learn.microsoft.com/zh-cn/dotnet/api/system.collections.ilist.isfixedsize?view=netframework-4.8.1&viewFallbackFrom=net-10.0
IList.IsFixedSize Property (System.Collections) | Microsoft Learn
Gets a value indicating whether the IList has a fixed size.
property systemilistcollectionsmicrosoftlearn
https://docs.ros.org/en/noetic/api/roscpp_traits/html/structros_1_1message__traits_1_1IsFixedSize.html
roscpp_traits: ros::message_traits::IsFixedSize M Struct Template Reference
traitsrosmessagestructtemplate