ConvertRegionsToLength #

Turn region tags (such as those produced by ExtractRegion/ExtractRegions) into numeric length tags.

[[step]]
    action = "ExtractRegion"
    out_label = "adapter"
    source = "read1"
    start = 0
    len = 12
    anchor = "Start"

[[step]]
    action = "ConvertRegionsToLength"
    out_label = "adapter_len"
    in_label = "adapter"

• The new tag stores the total span (in bases) covered by all regions on each read.
• Reads without the source tag receive a length of 0.
• label must be different from region_label; the step keeps the original region tag.