question: public boolean checkValidDest ( LayoutBlock currentBlock , LayoutBlock nextBlock , LayoutBlock destBlock , LayoutBlock destBlockn1 , int pathMethod ) throws jmri . JmriException { List < LayoutBlock > destList = new ArrayList < LayoutBlock > ( ) ; if ( destBlockn1 != null ) { destList . add ( destBlockn1 ) ; } try { return checkValidDest ( currentBlock , nextBlock , destBlock , destList , pathMethod ) ; } catch ( jmri . JmriException e ) { throw e ; } }
target:  Determines if one set of blocks is reachable from another set of blocks based upon the directions of the set of blocks. <p> This is used to help with identifying items such as signalmasts located at positionable points or turnouts are facing in the same direction as other given signalmasts. <p> Given the current block and the next block we can work out the direction of travel. Given the destBlock and the next block on, we can determine the whether the destBlock comes before the destBlock+1.