NATO map symbol for a friendly unit.  The proper shape of the armoured icon is supposed to be a lozenge shape, but an oval shape is often substituted, likely because it is easier to create in the draw function of many word processors.  The oval depection even appeared in US and Canadian doctrine standards for map symbols:
US Army's FM 1-02 Operational Terms and Graphics September 2004

Canadian Army's B-GL-331-003/FP-001 Military Symbols for Land Operations addendum 27 June 2005
Own work
CdnMCG