There are certain things even in our AIRPORT (NAIA) that those people there are asking for which are not required before.

Maybe some strict rules are to be or even being impelemented right now, as my brother went to Qatar last week, and the people at the AIRPORT are asking for? I don't know; my bother said, some of INVITATION LETTER??
It is really surprising but maybe, I assume, what they are asking for is the Affidavit of Support. Before, they aren't asking for this, but for someone to proceed without hitches, we have to be clear on this, and ask our Phil. Embassy here what is this.

My brother told me that when he said he doesn't have that invitation letter, the person approved his proceeding since he has already shown my WORKING VISA here, My passport, and my email form our office, which I used in sending him his e-ticket.

Inconsisitencies might arise as some people might not ask for this invitation letter (as if you are attending a b-day bash) or otherwise, but to make sure, coordinate with our embassy here for further details.