When importing NONMEM csv datasets into Phoenix, a # sign infront of an ID would be ignored and you might not be able to tell which row you wish to exclude from analysis. One way to resolve this is to save your csv dataset in Excel. Importing Excel files into a Phoenix project will consider the ID column text and retain the format. One can then filter those rows prior to analysis and obtain a list of filtered rows. One example of such filter would require a Data Wizard/Custom Transform such as: if(left(ID,1)<0,“Exclude”, “Include”) *This is example for numeric IDs like 101, 505, #505) - Other transforms might be needed for different type of data Then add a filter to Exclude the records with the flag “Exclude”.