Man pages matching name itclvars in section 3itcl:

itclvars.3itcl.en	debian 10 / itcl3-doc
itclvars.3itcl.en	debian 10 / tcl-itcl4-doc
itclvars.3itcl.en	debian 11 / itcl3-doc
itclvars.3itcl.en	debian 11 / tcl-itcl4-doc
itclvars.3itcl.en	debian 12 / itcl3-doc
itclvars.3itcl.en	debian 12 / tcl-itcl4-doc