I have an invisible disability essentially. Every time I attempt to get some accommodations people either make comments or ask questions because I am not in a wheelchair and don't look disabled even though I have severe disabilities. Of course I could tell the to f*ck off but I'm not a confrontational person and don't want to deal with all the lunatics out there. I'm wondering if there is a document to show that a person is in fact disabled for travel, besides handicapped pass.