Companies listed in mainland China have reached a historic milestone in their global operations. Total overseas revenues hit a record, with electronic and automobile giants such as Foxconn Technology Group and BYD among the top performers.Total overseas revenues of A-share companies approached 12.4 trillion yuan (US$1.8 trillion) last year, accounting for nearly 17 per cent of their total income – both figures representing all-time highs, according to data from state-backed newspaper Securities Times.A group of companies that have effectively localised their operations across continents is leading the charge, topped by PetroChina, the listed arm of state-owned China National Petroleum Corporation,…