There were (at least) two incarnations of Flex, implemented using hardware with writable microcode. The first was supplied by Logica to an RSRE design, and the second used an ICL PERQ. The microcode alone was responsible for storage allocation, deallocation and garbage collection. This immediately precluded a whole class of errors arising from the misuse (deliberate or accidental) of pointers. A notable feature of Flex was the tagged, write-once filestore. This allowed arbitrary code and data structures to be written and retrieved transparently, without recourse to external encodings. Data could thus be passed safely from program to program. In a similar way, remote capabilities allowed data and procedures on other machines to be accessed over a network connection, again without the application program being involved in external encodings of data, parameters or result values. The whole scheme allowed abstract data types to be safely implemented, as data items and the procedures permitted to access them could be bound together, and the resulting capability passed freely around. The capability would grant access to the procedures, but could not be used in any way to obtain access to the data. Another notable feature of Flex was the notion of shaky pointers, more recently often called weak references, which points to blocks of memory that could be freed at the next garbage collection. This is used for example for cached disc blocks or a list of spare procedure work-spaces. COMFLEX, a packet switching network capable of transmitting data at magnetic-disc speed, was developed alongside Flex. It made feasible the use of remote file-stores, remote capabilities, and remote procedure calls. Nontraditional student  A nontraditional student is a term originating in North America, that refers to a category of students at colleges and universities. The National Center for Education Statistics (NCES) notes that there are varying definitions of nontraditional student. Nontraditional students are contrasted with traditional students who "earn a high school diploma, enroll full time immediately after finishing high school, depend on parents for financial support, and either do not work during the school year or work part time". The NCES categorized anyone who satisfies at least one of the following as a nontraditional student:   By this definition, the NCES determined that 73% of all undergraduates in 1999–2000 could be considered nontraditional, representing the newly "typical" undergraduate. This remained consistent the following years: 72% in 2003–2004, 72% for 2007–2008, and 74% for 2011–2012.