Here are the data structures with brief descriptions:

[detail level 12]

Caliasbone_t
Caliastag_t
Calloc_chain
Callocatedoggpage_t
Canimatemodel_cache
Canimscene_t
Cbarrier_t
Cbeam_t
Cbenchmarkhistory_t
Cbih_leaf_t
Cbih_node_t
Cbih_t
Cblendweights_t
Ccachepic_t
Ccapturevideostate_avi_formatspecific_t
Ccapturevideostate_ogg_formatspecific_t
Cchallenge_t
Cchannel_t
Ccl_clientmovement_state_t
Ccl_downloadack_t
Ccl_effect_t
Ccl_iplog_item_t
Ccl_locnode_t
Ccl_soundstats_t
Ccl_video_subtitle_info_t
Cclient_state_t
Cclient_static_t
Cclient_t
Cclvideo_t
Ccmd_alias_t
Ccmd_buf_t
Ccmd_function_t
Ccmd_input_t
Ccmd_iter_t
Ccmd_state_t	Command interpreter state - the tokenizing and execution of commands, as well as pointers to which cvars and aliases they can access
Ccmd_userdefined_t	Container for user-defined QC functions and aliases, shared between different command interpreters
Ccolboxbrushf_t
Ccolbrushf_t
Ccollision_cachedtrace_parameters_t
Ccollision_cachedtrace_t
Ccolplanef_t
Ccolpointf_t
CCompressedImageCacheItem
Ccon_lineinfo_t
Ccon_text_info_t
Cconbuffer_t
Cconvex_builder_state_t
Cconvex_corner_t
Cconvex_face_t
Ccrypto_data_t
Ccrypto_storedhostkey_t
Ccrypto_t
Ccshift_t
Ccsqc_vidvars_t
Ccsqcentityframedb_t
Ccubemapinfo_t
CCurl_downloadinfo_t
CCURLMsg
Ccustomstat_t
Ccvar_hash_t
Ccvar_state_t
Ccvar_t
Cdaliasframe_t
Cdaliasframetype_t
Cdaliasgroup_t
Cdaliashdr_t
Cdaliasinterval_t
Cdaliasskingroup_t
Cdaliasskininterval_t
Cdaliasskintype_t
Cdebug_data_t
Cdecalsystem_t
Cdfield16_t
Cdfunction_t
Cdhlmdl_animevent_t
Cdhlmdl_animvalue_t
Cdhlmdl_attachment_t
Cdhlmdl_bodypart_t
Cdhlmdl_bone_controller_t
Cdhlmdl_bone_t
Cdhlmdl_header_t
Cdhlmdl_hitbox_t
Cdhlmdl_mesh_t
Cdhlmdl_sequence_description_t
Cdhlmdl_sequence_group_t
Cdhlmdl_sequence_header_t
Cdhlmdl_t
Cdhlmdl_texture_t
Cdhlmdl_trivert_t
Cdlight_t
Cdllfunction_t
Cdownloadinfo
Cdp_font_t
Cdp_fonts_t
Cdpackfile_t
Cdpackheader_t
Cdpmbone_t
Cdpmbonepose_t
Cdpmbonevert_t
Cdpmframe_t
Cdpmheader_t
Cdpmmesh_t
Cdpmvertex_t
Cdprograms_t
Cdprograms_v7_t
Cdpvsimpledecodestream_t
Cdrawqueuemesh_t
Cdsprite2_t
Cdsprite2frame_t
Cdsprite_t
Cdspriteframe_t
Cdspriteframetype_t
Cdspritegroup_t
Cdspritehl_t
Cdspriteinterval_t
Cdstatement16_t
Cdstatement32_t
Cdtriangle_t
Cdvpk_archive_md5_entry_t
Cdvpk_dir_entry_t
Cdvpk_header_v1_t
Cdvpk_header_v2_t
Cdvpk_other_md5_entry_t
Cdvpk_signature_entry_t
Cedict_engineprivate_t
Cembeddedpic_t
Centity_database4_commit_t
Centity_frame_t
Centity_frameinfo_t
Centity_persistent_t
Centity_render_t
Centity_state_t
Centity_t
Centityframe4_database_t
Centityframe5_changestate_t
Centityframe5_database_t
Centityframe5_packetlog_t
Centityframe_database_t
Centityframeqw_database_t
Centityframeqw_snapshot_t
Centvars_t
Cenvmapinfo_s
Cepisode_t
Ceventqueueitem_t
Cexplosion_t
Cextendtraceinfo_t
Cfindnonsolidlocationinfo_t
Cfont_incmap_t
Cfont_postprocess_t
Cfontfilecache_t
Cframeblend_t
Cframegroupblend_t
Cfssearch_t
Cft2_attachment_t
Cft2_font_map_t
Cft2_font_t
Cft2_kerning_t
Cft2_settings_t
CFT_BBox
CFT_Bitmap
CFT_Bitmap_Size
CFT_CharMapRec
CFT_FaceRec
CFT_Generic
CFT_Glyph_Metrics
CFT_GlyphSlotRec
CFT_Open_Args
CFT_Outline
CFT_Outline_Funcs
CFT_Parameter
CFT_Size_Metrics
CFT_Size_RequestRec
CFT_SizeRec
CFT_Vector
Cgamedir_t
Cgameinfo_t
Cgamelevels_t
Cgamemode_info_t
Cgl_state_t
Cglfunction_t
Cglmode_t
Cglobalvars_t
Cgltexture_t
Cgltexturepool_t
Cgltextureunit_t
Cglyph_slot_t
Chl2dheader_t
Chl2lump_t
Chost_static_t
Chull_t
Chullinfo_t
Chz_bitstream_read_t
Chz_bitstream_readblock_t
Chz_bitstream_readblocks_t
Cimageformat_t
Cin_bestweapon_info_t
Ciqmanim_t
Ciqmbounds_t
Ciqmextension_t
Ciqmheader_t
Ciqmjoint1_t
Ciqmjoint_t
Ciqmmesh_t
Ciqmpose1_t
Ciqmpose_t
Ciqmtriangle_t
Ciqmvertexarray_t
Cj_compress_ptr
Cj_decompress_ptr
Cjamdecodestream_t
Cjpeg_component_info
Cjpeg_destination_mgr
Cjpeg_error_mgr
Cjpeg_memory_mgr
Cjpeg_source_mgr
Ckbutton_t
Ckeyname_t
Clevel_t
Clhnetaddress_t
Clhnetaddressnative_t
Clhnetpacket_t
Clhnetsocket_t
Clibavwstream_t
Clightmaplight_t
Clightmapsample_t
Clightmaptriangle_t
Clightmapvertex_t
Clightstyle_t
Clink_t
Clistener_t
Cllist_t
Cloadingscreenstack_t
Clump_t
Clumpinfo_t
Cmatrix4x4_t
Cmclipnode_t
Cmd2_t
Cmd2frame_t
Cmd2stvert_t
Cmd2triangle_t
Cmd3frameinfo_t
Cmd3mesh_t
Cmd3modelheader_t
Cmd3shader_t
Cmd3tag_t
Cmd3vertex_t
Cmdef_t
Cmdfour_s
Cmdl_t
Cmedge_t
Cmemexpandablearray_array_t
Cmemexpandablearray_t
Cmemheader_t
Cmempool_t
Cmeshqueue_t
Cmfunction_t
Cmleaf_t
Cmmodel_t
Cmnode_t
Cmod_alloclightmap_row_t
Cmod_alloclightmap_state_t
CMod_MakeSortedSurfaces_qsortsurface_t
Cmodel_brush_lightstyleinfo_t
Cmodel_brush_t
Cmodel_brushq1_t
Cmodel_brushq3_t
Cmodel_sprite_t
Cmodel_t
Cmodlist_entry_t
Cmodloader_t
Cmovevars_t
Cmplane_t
Cmportal_t
Cmspriteframe_t
Cmstatement_t
Cmsurface_lightmapinfo_t
Cmsurface_t	Describes the textures to use on a range of triangles in the model, and mins/maxs (AABB) for culling
Cmtexinfo_t
Cmvertex_t
Cmwad_t
Cmy_destination_mgr
Cnamecache_s
Cnehahrademonames_t
►Cnetconn_t
Cnetconn_nq_s
Cnetconn_qw_s
Cnetgraphitem_t
Cobjvertex_t
Cogg_packet
Cogg_page
Cogg_stream_perchannel_t
Cogg_stream_persfx_t
Cogg_stream_state
Cogg_sync_state
Coggpack_buffer
COggVorbis_File
Cov_callbacks
Cov_decode_t
Cpack_t
Cpackfile_t
Cparticle_t
Cparticleeffectinfo_t
Cparticletexture_t
Cparticletype_t
Cpatchinfo_t
Cpatchtess_t
Cpcx_t
Cpk3_endOfCentralDir_t
Cplane_t
Cplayermove_t
Cpo_string_t
Cpo_t
Cportable_sampleframe_t	Exported for capturevideo so ogg can see all channels
Cportal_t
Cportalrecursioninfo_t
Cprotocolversioninfo_s
Cprvm_edict_private_t
Cprvm_edict_t
Cprvm_eval_t
Cprvm_prog_fieldoffsets_t
Cprvm_prog_funcoffsets_t
Cprvm_prog_garbagecollection_state_t
Cprvm_prog_globaloffsets_t
Cprvm_prog_t
Cprvm_required_field_t
Cprvm_stack_t
Cprvm_stringbuffer_t
Cpskaniminfo_t
Cpskanimkeys_t
Cpskboneinfo_t
Cpskchunk_t
Cpskface_t
Cpskmatt_t
Cpskpnts_t
Cpskpose_t
Cpskrawweights_t
Cpskvtxw_t
Cq2dheader_t
Cq2dmodel_t
Cq2wal_t
Cq3dbrush_t
Cq3dbrushside_ig_t
Cq3dbrushside_t
Cq3deffect_t
Cq3dface_t
Cq3dheader_t
Cq3dleaf_t
Cq3dlightgrid_t
Cq3dlightmap_t
Cq3dmeshvertex_t
Cq3dmodel_t
Cq3dnode_t
Cq3dplane_t
Cq3dpvs_t
Cq3dtexture_t
Cq3dvertex_t
Cq3mbrush_t
Cq3mbrushside_t
Cq3shader_data_t
Cq3shader_hash_entry_t
Cq3shaderinfo_deform_t
Cq3shaderinfo_layer_alphagen_t
Cq3shaderinfo_layer_rgbgen_t
Cq3shaderinfo_layer_t
Cq3shaderinfo_layer_tcgen_t
Cq3shaderinfo_layer_tcmod_t
Cqfile_t
Cqpic_t
Cr_bufferdata_buffer_t
Cr_decalsystem_splatqueue_t
Cr_framebufferstate_t
Cr_framedata_mem_t
Cr_glsl_permutation_t
Cr_meshbuffer_t
Cr_q1bsp_getlightinfo_t
Cr_qwskincache_t
Cr_refdef_scene_t
Cr_refdef_t
Cr_refdef_view_t
Cr_refdef_viewcache_t
Cr_rendertarget_t
Cr_shadow_bouncegrid_photon_path_t
Cr_shadow_bouncegrid_photon_t
Cr_shadow_bouncegrid_settings_t
Cr_shadow_bouncegrid_state_t
Cr_skinframe_t
Cr_viewport_t
Cr_waterstate_t
Cr_waterstate_waterplane_t
Crandomseed_t
Cratetable_t
CRecursiveHullCheckTraceInfo_t
Crendermodule_t
Crequirement
Crmesh_t
Crsurfacestate_t
Crtexture_t
Crtexturepool_t
Crtlight_particle_t
Crtlight_t
Cscoreboard_t
Cscr_touchscreenarea_t
Csearchpath_t	Search paths for files (including packages)
Cserver_cryptoconnect_t
Cserver_floodaddress_t
Cserver_static_t
Cserver_t
Csfx_t
Cshader_t
Cshadermodeinfo_t
Cshaderpermutationinfo_t
Cshadowmesh_t
Cshadowmeshvertexhash_t
Cshowlmp_t
Csizebuf_t
Cskeleton_t
Cskinfile_t
Cskinfileitem_t
Cskinframe_t
Csnd_buffer_t
Csnd_fetcher_t
Csnd_format_t
Csnd_ringbuffer_t
Cspeakerlayout_t
Cstringlist_t
Cstvert_t
Csuffixinfo_t
Csurfmesh_t
Csvbsp_node_t
Csvbsp_polygon_t
Csvbsp_t
Csvbspmesh_t
Csys_cleantime_t
Csys_t
CTargaHeader
Ctaskqueue_state_t
Ctaskqueue_state_thread_t
Ctaskqueue_task_t
Ctexture_shaderpass_t
Ctexture_t
Ctextypeinfo_t
Ctexvecvertex_t
Ctheora_comment	Comment header metadata
Ctheora_info	Theora bitstream info
Ctheora_state	Codec internal state and context
CThread_Atomic
Cthread_cond_t
Cthread_semaphore_t
Cthreadwrapper_t
Ctinydoubleplane_t
Ctinyplane_t	LadyHavoc: minimal plane structure
Ctrace_t
Ctridecal_t
Ctrivertx_t
Curi_to_prog_t
Cusercmd_t
Cvfs_t
Cvid_joystate_t
Cvid_mode_t
Cviddef_mode_t
Cviddef_support_t
Cviddef_t
Cvideo_resolution_t
Cvidfallback_s
Cvmparticlespawner_t
Cvmparticletheme_t
Cvorbis_block
Cvorbis_comment
Cvorbis_dsp_state
Cvorbis_info
Cwadinfo_t
Cwadstate_t
Cwavinfo_t
Cworld_physics_t
Cworld_t
Cxmp_channel
Cxmp_module
Cxmp_module_info
Cxmp_stream_perchannel_t
Cxmp_stream_persfx_t
Cyuv_buffer
Cz_stream
Cztoolkit_t
Czymbone_t
Czymlump_t
Czymscene_t
Czymtype1header_t
Czymvertex_t