[font style="font-family:'Georgia','Baskerville Old Face','Helvetica',fantasy;" size=4 color=teal]It is meant to include all the different forms of sexuality and gender that are different cis-heterosexuality without naming them specifically. Terms like Pan-sexual, Asexual*, two-spirit,Poly sexual, bigender, trigender, gender queer, agender, and so on.
Sources:
https://internationalspectrum.umich.edu/life/definitions
http://geneq.berkeley.edu/lgbt_resources_definiton_of_terms#queer
http://www.lgbt.ucla.edu/documents/LGBTTerminology.pdf
Of course some of these things were later added explicitly when it went from LGBTQ to LGBTQIA.
LGBTQIA=Lesbian, gay, bisexual, trangender, queer/questioning, intersex, Asexual/Agender/ and on occasion I have heard the A used for aromantic and ally
*On one of the sites I visit (AVEN) there is a debate on whether asexuality qualify as being queer or not. Some people (of a variety of orientations) there will argue vehemently that it should not be included, and others will just as passionately advocate it should be included. YMMV.[/font]