Fix TPV/TPD implementation

ext/FITSWCSFITSFilesExt.jl

@@ -35,7 +35,8 @@ function _set_fitsfiles_header_card!(dict::Dict{String, Any}, key::String, value
     isnothing(parsed) && return dict
 
     name, parsed_value = parsed
-    if name == "EXTVER" || name == "NAXES" || startswith(name, "AXIS.")
+    if name in ("EXTVER", "NAXES", "DOCORR") ||
+            any(prefix -> startswith(name, prefix), ("AXIS.", "OFFSET.", "SCALE.", "TPD.", "AUX."))
         dict["$(key).$(name)"] = parsed_value
     end
     return dict

ext/FITSWCSFITSIOExt.jl

@@ -35,7 +35,8 @@ function _set_fitsio_header_card!(dict::Dict{String, Any}, key::String, value)
     isnothing(parsed) && return dict
 
     name, parsed_value = parsed
-    if name == "EXTVER" || name == "NAXES" || startswith(name, "AXIS.")
+    if name in ("EXTVER", "NAXES", "DOCORR") ||
+            any(prefix -> startswith(name, prefix), ("AXIS.", "OFFSET.", "SCALE.", "TPD.", "AUX."))
         dict["$(key).$(name)"] = parsed_value
     end
     return dict

src/api.jl

@@ -33,9 +33,7 @@ matching the APE-14 convention.  For `SlicedWCSTransform`: the parent's
 matrix indexed by the kept axes.
 """
 function axis_correlation_matrix(wcs::WCSTransform{N}) where {N}
-    # If any pre-linear distortion is present (SIP, D2IM, CPDIS), we must be
-    # conservative: distortions can introduce arbitrary cross-axis coupling
-    # that isn't captured by the CD matrix alone.
+    # Any distortion stage may introduce cross-axis coupling not captured by CD.
     if has_distortion(wcs.pipeline)
         return fill(true, SMatrix{N, N, Bool})
     end

src/auxiliary_data.jl

@@ -67,7 +67,9 @@ function _paper_iv_lookup_spec(
     )
     dist_key = "$(dist_prefix)$(axis)$(alt_str)"
     haskey(header, dist_key) || return nothing
-    uppercase(String(header[dist_key])) == "LOOKUP" ||
+    dtype = uppercase(strip(String(header[dist_key])))
+    dtype == "TPD" && return nothing
+    dtype == "LOOKUP" ||
         throw(ArgumentError("unsupported Paper IV distortion type $(header[dist_key]) in $dist_key"))
 
     # Skip tables whose declared error is below the requested threshold.
@@ -154,10 +156,26 @@ function _header_references_tabular_axis(header::AbstractDict, alt_str::Abstract
 end
 
 function _header_references_external_wcs_data(header::AbstractDict, alt_str::AbstractString)
-    # Paper IV distortion keywords and TAB axes are the current external-data signals.
-    for key in keys(header)
+    suffix = uppercase(String(alt_str))
+
+    # Only lookup distortions require external arrays; TPD is header-resident.
+    for (key, value) in header
         key isa AbstractString || continue
-        is_lookup_distortion_keyword(key, alt_str) && return true
+        ukey = uppercase(String(key))
+        occursin(Regex("^D2IMDIS[1-9][0-9]*$(suffix)\$"), ukey) && return true
+        occursin(Regex("^D2IMERR[1-9][0-9]*$(suffix)\$"), ukey) && return true
+        ukey == "AXISCORR$(suffix)" && return true
+        if occursin(Regex("^CPDIS[1-9][0-9]*$(suffix)\$"), ukey)
+            uppercase(strip(String(value))) == "LOOKUP" && return true
+        end
+
+        # Undeclared DP/DQ records retain the legacy external-data guard, while
+        # records belonging to an explicit TPD function remain header-resident.
+        parameter = match(Regex("^D([PQ])([1-9][0-9]*)$(suffix)\\."), ukey)
+        isnothing(parameter) && continue
+        dist_prefix = parameter.captures[1] == "P" ? "CPDIS" : "CQDIS"
+        dist_key = "$(dist_prefix)$(parameter.captures[2])$(suffix)"
+        haskey(header, dist_key) && uppercase(strip(String(header[dist_key]))) == "TPD" || return true
     end
 
     return _header_references_tabular_axis(header, alt_str)