Thank you! If I am understanding you correctly, then the first method worked because everything in a SAS library is already a SAS data set (it is of type sas7bdat or whatever other implicit types are allowed). The third method is redundant and causes the implied name to be something like storm_summary.sas7bdat.sas7bdat, which does not exist. Is that a reasonable interpretation? Dave (newbie) ... View more

/* Using SASUniversityEdition with Windows 10 Prof for SAS Programming 1: Essentials Lesson 2: Accessing Data */   * This works; libname mylib "/folders/myfolders/sasuser.v94/EPG1V2/data"; proc contents data=mylib.storm_summary; run;   * and this works; proc contents data="/folders/myfolders/sasuser.v94/EPG1V2/data/storm_summary.sas7bdat"; run;   * but this gets an invalid data set name error; libname mylib "/folders/myfolders/sasuser.v94/EPG1V2/data"; proc contents data=mylib.storm_summary.sas7bdat; run; * I do not understand why the file extension must be entered into the second form; but cannot be entered into the third form. ; ... View more