Thanks to all for your responses regarding my question of why order() was behaving differently for me on my linux and solaris platforms. It seems that order() behaves according to the collating sequence and character set that the particular platform assumes. I mistakingly assumed that the function would behave the same regardless of the platform. I have briefly summarized the responses I received. Don MacQueen suggested that I try creating a text file outside of R with each of the characters on a separate line to see if the different operating systems' sort command on the file produced different results. James Holtman and Uwe Ligges both pointed to the fact that the character set and collating sequence could be different on each platform, which would affect the functionality of order(). Richard A. O'Keefe suggested that I check the settings of each environment by lookign at the variables LC_COLLATE and/or LANG. He also suggested a C program for me to run to check for plausible answers. -Raja