Here is a list of all variables with links to the structures/unions they belong to:

c : f_angl, imp_inv, qint, tint
c_angle : image
c_shift : image
calc_opts : cpmd
calc_time : project
calc_type : cpmd
camera_widg : glwin
cart_to_frac : box_info
cartesian : coord_file
carttofrac : lattice
cbuilder : glwin
cc : VideoStream
cell : builder_edition, project
cell_win : glwin
cextra : cell_info
cfile : Curve
ch : coord_edition
chain : atom
chain_max : glwin
chains : glwin
chains_model : coord_edition
charge : field_atom
checked : pixel
chem_prop : chemical_data
chemistry : project
chlab : coord_edition
cid : Curve
cloned : atom, atom_data
cloned_poly : image
clones : builder_edition, glwin
clones_to_be_picked : glwin
cmap : glwin
cmax : colormap, coord_info, Curve
cmin : colormap, coord_info, Curve
codec : video_options
col : glsl_program, screen_string
color : Fog
color_map : image
color_to_pick : glwin
colorp : glwin
colors : colormap
comp_vol : glwin
compb : volumes
constraints : field_molecule
coord : atom, atom_edition, atomic_object, coord_file, crystal_data, dummy_atom, project
coord_origin : space_group
coord_win : glwin
coordfile : project
cp2k_input : project
cparam : cell_edition
cpmd_input : project
create_shaders : glwin
cross : classical_field
crystal : cell_info
cs_combo : builder_edition
csdata : project
csearch : project
cshift : glwin
csparam : project
cst : coord_edition
csz : coord_edition
cubic : lattice
curve_hbox : Curve
curve_vbox : Curve
curves : project
custom_map : glwin
cut_this_slab : cell_edition
cutoffs : chemical_data