0001047469-98-004993 SC 13G 3 19980212 NASD 3DX TECHNOLOGIES INC 0000915518 1311 760386601 DE 1231 SC 13G 34 005-49753 98532803 12012 WICKCHESTER SUITE 250 HOUSTON TX 77079 2815793390 12012 WICKCHESTER SUITE 250 HOUSTON TX 77079 TCW GROUP INC 0000850401 SC 13G 865 SOUTH FIGUEROA ST LOS ANGELES CA 90017 865 SOUTH FIGUEROA STREET LOS ANGELES CA 90017 SC 13G 1 000104746998004993-001-seq1-sc-13g.txt SCHEDULE 13G EX-21 2 000104746998004993-002-seq2-ex-21.txt RELEVANT SUBSIDIARIES OF PARENT HOLDING COMPANY EX-99.1 3 000104746998004993-003-seq3-ex-99-1.txt JOINT FILING AGREEMENT