--- a/src/industry_map.h
+++ b/src/industry_map.h
@@ -119,6 +119,13 @@
 	SB(_m[tile].m1, 0, 2, value);
 }
 
+/**
+ * Get the industry graphics ID for the given industry tile as
+ * stored in the without translation.
+ * @param t the tile to get the gfx for
+ * @pre IsTileType(t, MP_INDUSTRY)
+ * @return the gfx ID
+ */
 static inline IndustryGfx GetCleanIndustryGfx(TileIndex t)
 {
 	assert(IsTileType(t, MP_INDUSTRY));

--- a/src/industrytype.h
+++ b/src/industrytype.h
@@ -181,6 +181,11 @@
 extern IndustrySpec _industry_specs[NUM_INDUSTRYTYPES];
 extern IndustryTileSpec _industry_tile_specs[NUM_INDUSTRYTILES];
 
+/**
+ * Do industry gfx ID translation for NewGRFs.
+ * @param gfx the type to get the override for.
+ * @return the gfx to actually work with.
+ */
 static inline IndustryGfx GetTranslatedIndustryTileID(IndustryGfx gfx)
 {
 	/* the 0xFF should be GFX_WATERTILE_SPECIALCHECK but for reasons of include mess,