Q about Build-Depends vs Build-Depends-Indep

[Peter S Galbraith <GalbraithP@dfo-mpo.gc.ca>]

The packaging manual (section 8.7) says:

 Build-Depends, Build-Conflicts 
    The Build-Depends and Build-Conflicts fields apply to the
    targets build, binary, binary-arch and binary-indep.

 Build-Depends-Indep, Build-Conflicts-Indep 
    The Build-Depends-Indep and Build-Conflicts-Indep fields
    apply to the targets binary and binary-indep.

Currently, my gri package has the following Build-Depends:

Build-Depends: debhelper, netcdfg-dev, imagemagick, gs, gs-fonts, 
  tetex-bin, texinfo

Most of those are needed for the binary-indep target (building
docs) and won't be needed by porters doing only the binary-arch
build.

But the docs don't say one of the Build-Depends applies only to
binary-arch, so what's the use?

Am I missing something?  Should I be doing:

Build-Depends: debhelper, netcdfg-dev
Build-Depends-Indep: debhelper, netcdfg-dev, imagemagick, gs, gs-fonts, 
  tetex-bin, texinfo


Confused,

Peter