Import Purchase Invoices (AP) from a text file.

I want to import Purchase Invoices (AP) from a text file. The Knowledgebase says this:

From https://support.na.sage.com/selfservice/viewdocument.do?noCount=true&externalId=10186&sliceId=1&cmd=displayKC&dialogID=105647&docType=kc&isLoadPublishedVer=&stateId=105649&docTypeID=DT_Article&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl

This articles describes how to import general journal entries only from a text file (CSV). Sage 50-Canadian Edition does not provide a text file method of importing actual transaction details such as invoices. If you have a third-party software developer, refer to the Sage 50-Canadian Edition SDK as there are some methods available to import transactions.

I have a third-party developer but I don't see where these other methods are described. Can you direct me? Thanks in advance.