It has been widely recognized that traditional transaction models with ACID(Atomicity, Consistency, Isolation and Durability) properties generally are not applicable to cooperative applications. Though many advanced transaction models have been proposed to address the problems, they are too database-centered or too rigid to be useful in real environments. This paper presents a new transaction model named CovaTM, which provides sophisticated but flexible control over cooperative process as well as support for error recovery and exception handling. The most distinguished feature of this model is that user intervention is explicitly introduced into transaction processing. This paper details the features and structural elements of this model. An example is also given to illustrate how it works in real world settings.