In a VECM, A $Y _ { t } - \theta X _ { t }$

Short Answer

In a VECM, a. past values of $Y _ { t } - \theta X _ { t }$ help to predict future values of $\Delta Y _ { t }$ and/or $\Delta X _ { t }$ .
b. errors are corrected for serial correlation using the Cochrane-Orcutt method.
c. current values of $Y _ { t } - \theta X _ { t }$ help to predict future values of $\Delta Y _ { t }$ and/or $\Delta X _ { t }$ .
d. VAR techniques, such as information criteria, no longer apply.