Hi everyone,   If I have a dataset that looks like the following (with ~5,000 rows). The VariableList contains strings with certain prefix ("string*") as well as other numbers and characters, always separated by space.       ID VariableList A1 stringA stringB 123 A2 stringA + stringB > stringC A3 stringA  A4 stringB stringC 456 A5 stringC stringD abc   And I want to search for units where in the VariableList, the words with prefix include words from a list ("stringA" or "stringB"), but no other prefixed words ("StringC", "StringD", etc). I don't care about the extra strings. So in this example, I want the new dataset to only contain      ID VariableList A1 stringA stringB 123 A3 stringA    I found a similar question (https://communities.sas.com/t5/SAS-Procedures/searching-words-in-a-variable/td-p/85846) and tried the PRX function as follows:   data have;    length ID $ 10 VariableList $ 50;    infile cards dsd dlm='|' truncover ;    input ID VariableList;    datalines; A1|stringA stringB 123 A2|stringA + stringB > stringC A3|stringA  A4|stringB stringC 456 A5|stringC stringD abc ; run;   %let matchString=stringA|stringB; data want;    set have;    where prxmatch("/\b(&matchString.)\b/", VariableList); run;   But this would find all the rows that contain stringA and stringB, including the ones that I don't want (A2 & A4). How do I go about excluding them? Thanks a lot!   ... View more