What does the RT² qPCR Primer Assay product information mean when it says that it recognizes another transcript of the same gene?

When a RT² qPCR Primer Assay recognizes another transcript of the same gene, the resulting signal by real-time or end-point detection represents the sum of the relative expression of all of the transcripts detected by the Primer Assay. When alternative transcripts or splice variants are known and annotated in the public databases, the RT² qPCR Primer Assay are designed to generate an amplicon in common to as many of those known transcripts as possible