There is an INFORMAT statement which associates a "default INFORMAT" to use with inputting a SAS variable and then also there is any specified INFORMAT that is coded on the SAS INPUT statement.
I was unable to locate any SAS-hosted DOC (at the SAS support website - using the Google advanced search argument below) that mentions the exact phrase(s) you quoted, unfortunately. Suggest you might code both options/parameters with different INFORMAT values (for distinction) and observe what SAS code is being generated to get a clearer understanding.
Scott Barry
SBBWorks, Inc.
+"enterprise guide" +4.2 +informat +source +output site:sas.com