Gencode 3c annotation file "gencode.v3c.annotation.GRCh37.gtf" is downloaded from: ftp://ftp.sanger.ac.uk/pub/gencode, and is then parsed to generate "interval" and "isoformMap" files. Note that the gtf file is 1-based inclusive.
"interval" files are generated using either CDS or Exon features in "gencode.v3c.annotation.GRCh37.gtf". "interval" files contain annotations for a transcript, the 8 columns are transcript ID,chromosome,strand,start,end,exon/CDS number,starts and ends for each individual exon/CDS. Note that "interval" file coordinates are 0-based, half-open(start position is inclusive, and end position is not inclusive).
"isoformMap" files are generated using "interval" files, the transcripts with same gene ID are clustered together. The 2 columns are gene cluster ID and transcript ID.

Files are generated by Lukas Habbeger@Gersteinlab.

Files based on CDS annotations: 
gencode.v3c.annotation.GRCh37.cds.gtpc.ttpc.interval    
gencode.v3c.annotation.GRCh37.cds.gtpc.ttpc.isoformMap  

Files based on Exon annotations:
gencode.v3c.annotation.GRCh37.exon.gtpc.ttpc.interval   
gencode.v3c.annotation.GRCh37.exon.gtpc.ttpc.isoformMap


Please note that:
gtpc means: gene type = protein coding
ttpc means: transcript type = protein coding
Hence, entries in the gtf file that match this description are included in the interval files.