g: global depth; dbase: base address of directory; dold: old directory entry;
ibits: bit string; K: primary key; K': pseudo key in bit string; D: directory; dentry: a directory entry pointer; dnew: new directory entry; vb: verification bits of directory entry; ps: page status field of a directory entry; pageadr address of desired page; Id: local depth of a page; tstatus: transaction status (blocked or running); pagecapacity: maximum number of records in a page; dircontraction, dirfree, pagefree, siblingfound, result, found: boolean