This PDF file details the different squad formations:

http://www.globalsecurity.org/military/library/policy/army/fm/5-10/appa.pdf#xml=http://www.globalsecurity.org/cgi-bin/texis.cgi/webinator/search/pdfhi.txt?query=formations&pr=default&prox=page&rorder=500&rprox=500&rdfreq=500&rwfreq=500&rlead=500&rdepth=0&sufs=0&order=r&cq=&id=4bdd67b71a