Temporal text concatenation

{text,ttext} || {text,ttext}: ttext

SELECT ttext '[AA@2012-01-01, AA@2012-01-04)' || text 'B';
-- "["AAB"@2012-01-01, "AAB"@2012-01-04)"
SELECT ttext '[AA@2012-01-01, AA@2012-01-04)' || ttext '[BB@2012-01-02, BB@2012-01-05)';
-- "["AABB"@2012-01-02, "AABB"@2012-01-04)"
SELECT ttext '[A@2012-01-01, B@2012-01-03, C@2012-01-04]' ||
  ttext '{[D@2012-01-01, D@2012-01-02), [E@2012-01-02, E@2012-01-04)}';
-- "{["DA"@2012-01-01, "EA"@2012-01-02, "EB"@2012-01-03, "EB"@2012-01-04)}"

Transform to uppercase

upper(ttext): ttext

SELECT upper(ttext '[AA@2000-01-01, bb@2000-01-02]');
-- "["AA"@2000-01-01, "BB"@2000-01-02]"

Transform to lowercase

lower(ttext): ttext

SELECT lower(ttext '[AA@2000-01-01, bb@2000-01-02]');
-- "["aa"@2000-01-01, "bb"@2000-01-02]"