The .gtf file contains MVP mapping data for the
Human Epigenome Project (HEP) in the format described below.
Column 2 may be decoded thus:
- for CpG Trace trace_id:tissue_name
- for CpG Variation trace_id:position_in_trace
- for CpG Analysis Sanger:epi_id_number
The Analysis co-ordinates are those of the amplicon
of the given Sanger:epi_id_number.
'CpG Variation' refers to the position of the C of