R version 2.6.2 (2008-02-08)
Copyright (C) 2008 The R Foundation for Statistical Computing
ISBN 3-900051-07-0

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> x <- c(jan/00,feb/00,mrt/00,apr/00,mei/00,jun/00,jul/00,aug/00,sep/00,okt/00,nov/00,dec/00,jan/01,feb/01,mrt/01,apr/01,mei/01,jun/01,jul/01,aug/01,sep/01,okt/01,nov/01,dec/01,jan/02,feb/02,mrt/02,apr/02,mei/02,jun/02,jul/02,aug/02,sep/02,okt/02,nov/02,dec/02,jan/03,feb/03,mrt/03,apr/03,mei/03,jun/03,jul/03,aug/03,sep/03,okt/03,nov/03,dec/03,jan/04,feb/04,mrt/04,apr/04,mei/04,jun/04,jul/04,aug/04,sep/04,okt/04,nov/04,dec/04,jan/05,feb/05,mrt/05,apr/05,mei/05,jun/05,jul/05,aug/05,sep/05,okt/05,nov/05,dec/05)
Error: object "jan" not found
Execution halted