0000912057-99-000251 SC 13G/A 3 19990212 3DX TECHNOLOGIES INC 0000915518 1311 760386601 DE 1231 SC 13G/A 34 005-49753 99532860 12012 WICKCHESTER SUITE 250 HOUSTON TX 77079 2815793398 12012 WICKCHESTER SUITE 250 HOUSTON TX 77079 TCW GROUP INC 0000850401 SC 13G/A 865 SOUTH FIGUEROA ST LOS ANGELES CA 90017 865 SOUTH FIGUEROA STREET LOS ANGELES CA 90017 SC 13G/A 1 000091205799000251-001-seq1-sc-13g-a.txt SCHEDULE 13G/A EX-21 2 000091205799000251-002-seq2-ex-21.txt RELEVANT SUBSIDIARIES OF PARENT HOLDING COMPANY EX-99.1 3 000091205799000251-003-seq3-ex-99-1.txt JOINT FILING AGREEMENT