• The setting for HeaderDisplayFunction can be any pure function.
• With the option HeaderDisplayFunctionf, the specified function will be applied to all headers in the dataset before displaying them.
• With the option HeaderDisplayFunctionf, the displayed header is given by f[header,position,dataset].
• The settings for HeaderDisplayFunction can be given as follows to apply separately to different items:
• spec apply spec to all headers
  {spec₁,spec₂,…,spec_n} apply spec_k to headers at dataset level k
  {spec_(1),spec_(2),...,spec_(n), rules} also allow explicit rules for individual headers
• The spec_k can have the following forms:
• {s₁,s₂,…,s_n} use s₁ through s_n; then use defaults
  {{c}} use c in all cases
  {{c₁,c₂}} alternate between c₁ and c₂
  {{c₁,c₂,…}} cycle through all c_i
  {s,{c}} use s, then repeatedly use c
  {s₁,{c},s_n} use s₁, then repeatedly use c, but use s_n at the end
  {s₁,s₂,…,{c₁,c₂,…},s_m,…,s_n} use the first sequence of s_i at the beginning, then cyclically use the c_i, then use the last sequence of s_i at the end
  {s₁,s₂,…,{},s_m,…,s_n} use the first sequence of s_i at the beginning and the last sequence at the end
• Rules have the form ispec, where i specifies a position in the dataset.
• Positions can be patterns.
• The position of a header can be read at the bottom of a dataset when you hover over the header.
• If the left-hand side of a rule is not a list, the setting is applied to any position that contains the left-hand side as a key or index.

Basic Examples  (1)

Possible Issues  (1)