Receiver File Adapter - Append mode

Hello All,

I have a scenario IDOC to File . On the receiver file adapter I have enabled APPEND options.

1) My doubt is , during the append of first message if another message also tries to append then how does PI work in this scenario ?

2) I saw that my subsequent messages were ending up either in waiting or delivering stage when I tried to trigger 5 to 10 idocs at the same time. Only 1st idoc got appended successfully and the rest had the status delivering.

What is the significance if I enable Orders at runtime in Interface Determination. Will it have any use in processing the message as EOIO.

Thanks in advance.