Harmonization of procedures for the whole region, however, remained a challenge because of various factors, such as differing geographical and infrastructure requirements, differing levels of development, and differing resource constraints.
不过，由于存在种种因素，例如地域和基础设施要求的不同、发展水平的差异以及资源制约因素的区别，统一整个地区的手续仍然是一项挑战。