Inserting within the inner profile of a rear corner post is?

Inserting within the inner profile of a rear corner post is not permitted because this practice compromises the structural integrity of the container. The rear corner post is a critical component of the container's overall strength and stability. Altering or inserting anything within this area could interfere with its ability to withstand the forces experienced during transport, potentially leading to failure under load.

The IICL standards are designed to ensure that containers maintain their structural integrity and safety throughout their usage. Therefore, any modification, especially within critical structural areas like the inner profile of a rear corner post, is specifically prohibited to uphold these safety and structural requirements. This is why the answer emphasizes that such actions should not take place.